diff --git a/src/Stats.cc b/src/Stats.cc
index 26cd4af2fa..ccf8433ae3 100644
--- a/src/Stats.cc
+++ b/src/Stats.cc
@@ -211,9 +211,9 @@ void ProfileLogger::Log()
 			                current_timers[i]));
 		}
 
-	file->Write(fmt("%0.6f Threads: current=%d\n", network_time, thread_mgr->NumThreads()));
+	file->Write(fmt("%0.6f Threads: current=%d\n", network_time, zeek::thread_mgr->NumThreads()));
 
-	const threading::Manager::msg_stats_list& thread_stats = thread_mgr->GetMsgThreadStats();
+	const threading::Manager::msg_stats_list& thread_stats = zeek::thread_mgr->GetMsgThreadStats();
 	for ( threading::Manager::msg_stats_list::const_iterator i = thread_stats.begin();
 	      i != thread_stats.end(); ++i )
 		{
diff --git a/src/Val.cc b/src/Val.cc
index fde6db8ad0..cd5a5addab 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -489,7 +489,8 @@ TableValPtr Val::GetRecordFields()
 	}
 
 // This is a static method in this file to avoid including rapidjson's headers in Val.h because they're huge.
-static void BuildJSON(threading::formatter::JSON::NullDoubleWriter& writer, Val* val, bool only_loggable=false, RE_Matcher* re=nullptr, const string& key="")
+static void BuildJSON(zeek::threading::formatter::JSON::NullDoubleWriter& writer, Val* val,
+                      bool only_loggable=false, RE_Matcher* re=nullptr, const string& key="")
 	{
 	if ( !key.empty() )
 		writer.Key(key);
@@ -585,7 +586,7 @@ static void BuildJSON(threading::formatter::JSON::NullDoubleWriter& writer, Val*
 				else
 					{
 					rapidjson::StringBuffer buffer;
-					threading::formatter::JSON::NullDoubleWriter key_writer(buffer);
+					zeek::threading::formatter::JSON::NullDoubleWriter key_writer(buffer);
 					BuildJSON(key_writer, entry_key, only_loggable, re);
 					string key_str = buffer.GetString();
 
@@ -689,7 +690,7 @@ static void BuildJSON(threading::formatter::JSON::NullDoubleWriter& writer, Val*
 StringValPtr Val::ToJSON(bool only_loggable, RE_Matcher* re)
 	{
 	rapidjson::StringBuffer buffer;
-	threading::formatter::JSON::NullDoubleWriter writer(buffer);
+	zeek::threading::formatter::JSON::NullDoubleWriter writer(buffer);
 
 	BuildJSON(writer, this, only_loggable, re, "");
 
diff --git a/src/broker/Data.cc b/src/broker/Data.cc
index 19eaed9311..6da27630ee 100644
--- a/src/broker/Data.cc
+++ b/src/broker/Data.cc
@@ -1264,7 +1264,7 @@ bool bro_broker::RecordIterator::DoUnserialize(const broker::data& data)
 	return true;
 	}
 
-broker::data bro_broker::threading_field_to_data(const threading::Field* f)
+broker::data bro_broker::threading_field_to_data(const zeek::threading::Field* f)
 	{
 	auto name = f->name;
 	auto type = static_cast<uint64_t>(f->type);
@@ -1279,7 +1279,7 @@ broker::data bro_broker::threading_field_to_data(const threading::Field* f)
 	return broker::vector({name, secondary, type, subtype, optional});
 	}
 
-threading::Field* bro_broker::data_to_threading_field(broker::data d)
+zeek::threading::Field* bro_broker::data_to_threading_field(broker::data d)
 	{
 	if ( ! caf::holds_alternative<broker::vector>(d) )
 		return nullptr;
@@ -1297,9 +1297,9 @@ threading::Field* bro_broker::data_to_threading_field(broker::data d)
 	if ( secondary != broker::nil && ! caf::holds_alternative<std::string>(secondary) )
 		return nullptr;
 
-	return new threading::Field(name->c_str(),
-				    secondary != broker::nil ? caf::get<std::string>(secondary).c_str() : nullptr,
-				    static_cast<zeek::TypeTag>(*type),
-				    static_cast<zeek::TypeTag>(*subtype),
-				    *optional);
+	return new zeek::threading::Field(name->c_str(),
+	                                  secondary != broker::nil ? caf::get<std::string>(secondary).c_str() : nullptr,
+	                                  static_cast<zeek::TypeTag>(*type),
+	                                  static_cast<zeek::TypeTag>(*subtype),
+	                                  *optional);
 	}
diff --git a/src/broker/Data.h b/src/broker/Data.h
index cbd136d35e..426496b467 100644
--- a/src/broker/Data.h
+++ b/src/broker/Data.h
@@ -6,10 +6,13 @@
 #include "Expr.h"
 
 ZEEK_FORWARD_DECLARE_NAMESPACED(ODesc, zeek);
-
+namespace zeek::threading {
+	struct Value;
+	struct Field;
+}
 namespace threading {
-struct Value;
-struct Field;
+	using Value [[deprecated("Remove in v4.1. Use zeek::threading::Value.")]] = zeek::threading::Value;
+	using Field [[deprecated("Remove in v4.1. Use zeek::threading::Field.")]] = zeek::threading::Field;
 }
 
 namespace bro_broker {
@@ -65,34 +68,34 @@ broker::expected<broker::data> val_to_data(const zeek::Val* v);
 zeek::ValPtr data_to_val(broker::data d, zeek::Type* type);
 
 /**
- * Convert a Bro threading::Value to a Broker data value.
- * @param v a Bro threading::Value.
- * @return a Broker data value if the Bro threading::Value could be converted to one.
+ * Convert a zeek::threading::Value to a Broker data value.
+ * @param v a zeek::threading::Value.
+ * @return a Broker data value if the zeek::threading::Value could be converted to one.
  */
-broker::expected<broker::data> threading_val_to_data(const threading::Value* v);
+broker::expected<broker::data> threading_val_to_data(const zeek::threading::Value* v);
 
 /**
- * Convert a Bro threading::Field to a Broker data value.
- * @param f a Bro threading::Field.
- * @return a Broker data value if the Bro threading::Field could be converted to one.
+ * Convert a zeek::threading::Field to a Broker data value.
+ * @param f a zeek::threading::Field.
+ * @return a Broker data value if the zeek::threading::Field could be converted to one.
  */
-broker::data threading_field_to_data(const threading::Field* f);
+broker::data threading_field_to_data(const zeek::threading::Field* f);
 
 /**
- * Convert a Broker data value to a Bro threading::Value.
+ * Convert a Broker data value to a zeek::threading::Value.
  * @param d a Broker data value.
- * @return a pointer to a new Bro threading::Value or a nullptr if the conversion was not
+ * @return a pointer to a new zeek::threading::Value or a nullptr if the conversion was not
  * possible.
  */
-threading::Value* data_to_threading_val(broker::data d);
+zeek::threading::Value* data_to_threading_val(broker::data d);
 
 /**
- * Convert a Broker data value to a Bro threading::Value.
+ * Convert a Broker data value to a zeek::threading::Value.
  * @param d a Broker data value.
- * @return a pointer to a new Bro threading::Value or a nullptr if the conversion was not
+ * @return a pointer to a new zeek::threading::Value or a nullptr if the conversion was not
  * possible.
  */
-threading::Field* data_to_threading_field(broker::data d);
+zeek::threading::Field* data_to_threading_field(broker::data d);
 
 /**
  * A Bro value which wraps a Broker data value.
diff --git a/src/broker/Manager.cc b/src/broker/Manager.cc
index 1b23deb7d4..5f92b4f56d 100644
--- a/src/broker/Manager.cc
+++ b/src/broker/Manager.cc
@@ -494,7 +494,7 @@ bool Manager::PublishIdentifier(std::string topic, std::string id)
 
 bool Manager::PublishLogCreate(zeek::EnumVal* stream, zeek::EnumVal* writer,
                                const zeek::logging::WriterBackend::WriterInfo& info,
-                               int num_fields, const threading::Field* const * fields,
+                               int num_fields, const zeek::threading::Field* const * fields,
                                const broker::endpoint_info& peer)
 	{
 	if ( bstate->endpoint.is_shutdown() )
@@ -550,7 +550,7 @@ bool Manager::PublishLogCreate(zeek::EnumVal* stream, zeek::EnumVal* writer,
 	}
 
 bool Manager::PublishLogWrite(zeek::EnumVal* stream, zeek::EnumVal* writer, string path,
-                              int num_fields, const threading::Value* const * vals)
+                              int num_fields, const zeek::threading::Value* const * vals)
 	{
 	if ( bstate->endpoint.is_shutdown() )
 		return true;
@@ -1260,7 +1260,7 @@ bool bro_broker::Manager::ProcessLogCreate(broker::zeek::LogCreate lc)
 		}
 
 	auto num_fields = fields_data->size();
-	auto fields = new threading::Field* [num_fields];
+	auto fields = new zeek::threading::Field* [num_fields];
 
 	for ( size_t i = 0; i < num_fields; ++i )
 		{
@@ -1344,11 +1344,11 @@ bool bro_broker::Manager::ProcessLogWrite(broker::zeek::LogWrite lw)
 		return false;
 		}
 
-	auto vals = new threading::Value* [num_fields];
+	auto vals = new zeek::threading::Value* [num_fields];
 
 	for ( int i = 0; i < num_fields; ++i )
 		{
-		vals[i] = new threading::Value;
+		vals[i] = new zeek::threading::Value;
 
 		if ( ! vals[i]->Read(&fmt) )
 			{
diff --git a/src/broker/Manager.h b/src/broker/Manager.h
index eb8dd00957..502be415fb 100644
--- a/src/broker/Manager.h
+++ b/src/broker/Manager.h
@@ -189,7 +189,7 @@ public:
 	bool PublishLogCreate(zeek::EnumVal* stream, zeek::EnumVal* writer,
 	                      const zeek::logging::WriterBackend::WriterInfo& info,
 	                      int num_fields,
-	                      const threading::Field* const * fields,
+	                      const zeek::threading::Field* const * fields,
 	                      const broker::endpoint_info& peer = NoPeer);
 
 	/**
@@ -205,7 +205,7 @@ public:
 	 */
 	bool PublishLogWrite(zeek::EnumVal* stream, zeek::EnumVal* writer,
 	                     std::string path, int num_vals,
-	                     const threading::Value* const * vals);
+	                     const zeek::threading::Value* const * vals);
 
 	/**
 	 * Automatically send an event to any interested peers whenever it is
diff --git a/src/input/Manager.cc b/src/input/Manager.cc
index 86aa0b3f9d..7e13d9e5c6 100644
--- a/src/input/Manager.cc
+++ b/src/input/Manager.cc
@@ -23,8 +23,8 @@
 #include "../threading/SerialTypes.h"
 
 using namespace std;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input {
 
diff --git a/src/input/ReaderBackend.cc b/src/input/ReaderBackend.cc
index 6669c5127e..ec7e46dc80 100644
--- a/src/input/ReaderBackend.cc
+++ b/src/input/ReaderBackend.cc
@@ -4,8 +4,8 @@
 #include "ReaderFrontend.h"
 #include "Manager.h"
 
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input {
 
diff --git a/src/input/readers/ascii/Ascii.cc b/src/input/readers/ascii/Ascii.cc
index 5eddd5b399..5330ffb4a7 100644
--- a/src/input/readers/ascii/Ascii.cc
+++ b/src/input/readers/ascii/Ascii.cc
@@ -12,10 +12,9 @@
 
 #include "threading/SerialTypes.h"
 
-using namespace threading;
 using namespace std;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input::reader::detail {
 
@@ -114,8 +113,8 @@ bool Ascii::DoInit(const ReaderInfo& info, int num_fields, const Field* const* f
 	if ( set_separator.size() != 1 )
 		Error("set_separator length has to be 1. Separator will be truncated.");
 
-	formatter::Ascii::SeparatorInfo sep_info(separator, set_separator, unset_field, empty_field);
-	formatter = unique_ptr<threading::formatter::Formatter>(new formatter::Ascii(this, sep_info));
+	zeek::threading::formatter::Ascii::SeparatorInfo sep_info(separator, set_separator, unset_field, empty_field);
+	formatter = unique_ptr<zeek::threading::Formatter>(new zeek::threading::formatter::Ascii(this, sep_info));
 
 	return DoUpdate();
 	}
@@ -368,7 +367,7 @@ bool Ascii::DoUpdate()
 			if ( ! fit->present )
 				{
 				// add non-present field
-				fields[fpos] =  new Value((*fit).type, false);
+				fields[fpos] = new Value((*fit).type, false);
 				fpos++;
 				continue;
 				}
diff --git a/src/input/readers/ascii/Ascii.h b/src/input/readers/ascii/Ascii.h
index f3fa4f6c02..8522b273c1 100644
--- a/src/input/readers/ascii/Ascii.h
+++ b/src/input/readers/ascii/Ascii.h
@@ -82,7 +82,7 @@ private:
 	bool fail_on_file_problem;
 	std::string path_prefix;
 
-	std::unique_ptr<threading::formatter::Formatter> formatter;
+	std::unique_ptr<zeek::threading::Formatter> formatter;
 };
 
 } // namespace zeek::input::reader::detail
diff --git a/src/input/readers/benchmark/Benchmark.cc b/src/input/readers/benchmark/Benchmark.cc
index 439a03a8fc..783e43b479 100644
--- a/src/input/readers/benchmark/Benchmark.cc
+++ b/src/input/readers/benchmark/Benchmark.cc
@@ -29,7 +29,7 @@ Benchmark::Benchmark(zeek::input::ReaderFrontend *frontend) : zeek::input::Reade
 	heartbeatstarttime = 0;
 	heartbeat_interval = double(zeek::BifConst::Threading::heartbeat_interval);
 
-	ascii = new threading::formatter::Ascii(this, threading::formatter::Ascii::SeparatorInfo());
+	ascii = new zeek::threading::formatter::Ascii(this, zeek::threading::formatter::Ascii::SeparatorInfo());
 	}
 
 Benchmark::~Benchmark()
@@ -43,7 +43,7 @@ void Benchmark::DoClose()
 	{
 	}
 
-bool Benchmark::DoInit(const ReaderInfo& info, int num_fields, const Field* const* fields)
+bool Benchmark::DoInit(const ReaderInfo& info, int num_fields, const zeek::threading::Field* const* fields)
 	{
 	num_lines = atoi(info.source);
 
@@ -88,7 +88,7 @@ bool Benchmark::DoUpdate()
 	int linestosend = num_lines * heartbeat_interval;
 	for ( int i = 0; i < linestosend; i++ )
 		{
-		Value** field = new Value*[NumFields()];
+		zeek::threading::Value** field = new zeek::threading::Value*[NumFields()];
 		for  (int j = 0; j < NumFields(); j++ )
 			field[j] = EntryToVal(Fields()[j]->type, Fields()[j]->subtype);
 
@@ -124,9 +124,9 @@ bool Benchmark::DoUpdate()
 	return true;
 }
 
-threading::Value* Benchmark::EntryToVal(zeek::TypeTag type, zeek::TypeTag subtype)
+zeek::threading::Value* Benchmark::EntryToVal(zeek::TypeTag type, zeek::TypeTag subtype)
 	{
-	Value* val = new Value(type, subtype, true);
+	auto* val = new zeek::threading::Value(type, subtype, true);
 
 	// basically construct something random from the fields that we want.
 
@@ -189,7 +189,7 @@ threading::Value* Benchmark::EntryToVal(zeek::TypeTag type, zeek::TypeTag subtyp
 		// how many entries do we have...
 		unsigned int length = random() / (RAND_MAX / 15);
 
-		Value** lvals = new Value* [length];
+		zeek::threading::Value** lvals = new zeek::threading::Value* [length];
 
 		if ( type == zeek::TYPE_TABLE )
 			{
@@ -209,7 +209,7 @@ threading::Value* Benchmark::EntryToVal(zeek::TypeTag type, zeek::TypeTag subtyp
 
 		for ( unsigned int pos = 0; pos < length; pos++ )
 			{
-			Value* newval = EntryToVal(subtype, zeek::TYPE_ENUM);
+			zeek::threading::Value* newval = EntryToVal(subtype, zeek::TYPE_ENUM);
 			if ( newval == nullptr )
 				{
 				Error("Error while reading set");
@@ -250,10 +250,10 @@ bool Benchmark::DoHeartbeat(double network_time, double current_time)
 			if ( multiplication_factor != 1 || add != 0 )
 				{
 				// we have to document at what time we changed the factor to what value.
-				Value** v = new Value*[2];
-				v[0] = new Value(zeek::TYPE_COUNT, true);
+				zeek::threading::Value** v = new zeek::threading::Value*[2];
+				v[0] = new zeek::threading::Value(zeek::TYPE_COUNT, true);
 				v[0]->val.uint_val = num_lines;
-				v[1] = new Value(zeek::TYPE_TIME, true);
+				v[1] = new zeek::threading::Value(zeek::TYPE_TIME, true);
 				v[1]->val.double_val = CurrTime();
 
 				SendEvent("lines_changed", 2, v);
diff --git a/src/input/readers/benchmark/Benchmark.h b/src/input/readers/benchmark/Benchmark.h
index fbf68a849c..d0c0c7530b 100644
--- a/src/input/readers/benchmark/Benchmark.h
+++ b/src/input/readers/benchmark/Benchmark.h
@@ -39,7 +39,7 @@ private:
 	double timedspread;
 	double heartbeat_interval;
 
-	threading::formatter::Ascii* ascii;
+	zeek::threading::formatter::Ascii* ascii;
 };
 
 } // namespace zeek::input::reader
diff --git a/src/input/readers/binary/Binary.cc b/src/input/readers/binary/Binary.cc
index 843ada1229..fa1108c9c0 100644
--- a/src/input/readers/binary/Binary.cc
+++ b/src/input/readers/binary/Binary.cc
@@ -8,8 +8,8 @@
 #include "threading/SerialTypes.h"
 
 using namespace std;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input::reader::detail {
 
diff --git a/src/input/readers/config/Config.cc b/src/input/readers/config/Config.cc
index 6a38bce49b..10c6621995 100644
--- a/src/input/readers/config/Config.cc
+++ b/src/input/readers/config/Config.cc
@@ -15,9 +15,8 @@
 #include "input/Manager.h"
 #include "threading/SerialTypes.h"
 
-using namespace threading;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input::reader::detail {
 
@@ -72,8 +71,9 @@ bool Config::DoInit(const ReaderInfo& info, int num_fields, const Field* const*
 	empty_field.assign( (const char*) zeek::BifConst::InputConfig::empty_field->Bytes(),
 	                   zeek::BifConst::InputConfig::empty_field->Len());
 
-	formatter::Ascii::SeparatorInfo sep_info("\t", set_separator, "", empty_field);
-	formatter = std::unique_ptr<threading::formatter::Formatter>(new formatter::Ascii(this, sep_info));
+	zeek::threading::formatter::Ascii::SeparatorInfo sep_info("\t", set_separator, "", empty_field);
+	formatter = std::unique_ptr<zeek::threading::Formatter>(
+		new zeek::threading::formatter::Ascii(this, sep_info));
 
 	return DoUpdate();
 	}
diff --git a/src/input/readers/config/Config.h b/src/input/readers/config/Config.h
index 53d47be7ae..fdfa62d08c 100644
--- a/src/input/readers/config/Config.h
+++ b/src/input/readers/config/Config.h
@@ -49,7 +49,7 @@ private:
 	std::string set_separator;
 	std::string empty_field;
 
-	std::unique_ptr<threading::formatter::Formatter> formatter;
+	std::unique_ptr<zeek::threading::Formatter> formatter;
 	std::unordered_map<std::string, std::tuple<zeek::TypeTag, zeek::TypeTag>> option_types;
 	std::unordered_map<std::string, std::string> option_values;
 };
diff --git a/src/input/readers/raw/Raw.cc b/src/input/readers/raw/Raw.cc
index d4fc4f7b87..9628429ffc 100644
--- a/src/input/readers/raw/Raw.cc
+++ b/src/input/readers/raw/Raw.cc
@@ -20,8 +20,8 @@ extern "C" {
 #include "setsignal.h"
 }
 
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input::reader::detail {
 
diff --git a/src/input/readers/sqlite/SQLite.cc b/src/input/readers/sqlite/SQLite.cc
index ab5458d640..4491472ead 100644
--- a/src/input/readers/sqlite/SQLite.cc
+++ b/src/input/readers/sqlite/SQLite.cc
@@ -15,8 +15,8 @@
 
 #include "threading/SerialTypes.h"
 
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::input::reader::detail {
 
@@ -39,8 +39,8 @@ SQLite::SQLite(zeek::input::ReaderFrontend *frontend)
 			zeek::BifConst::InputSQLite::empty_field->Len()
 			);
 
-	io = new threading::formatter::Ascii(this, threading::formatter::Ascii::SeparatorInfo(std::string(),
-		      set_separator, unset_field, empty_field));
+	io = new zeek::threading::formatter::Ascii(this, zeek::threading::formatter::Ascii::SeparatorInfo(
+		                                           std::string(), set_separator, unset_field, empty_field));
 	}
 
 SQLite::~SQLite()
diff --git a/src/input/readers/sqlite/SQLite.h b/src/input/readers/sqlite/SQLite.h
index c38b2b1bb1..8fb1a6a00e 100644
--- a/src/input/readers/sqlite/SQLite.h
+++ b/src/input/readers/sqlite/SQLite.h
@@ -21,7 +21,7 @@ public:
 	static zeek::input::ReaderBackend* Instantiate(zeek::input::ReaderFrontend* frontend) { return new SQLite(frontend); }
 
 protected:
-	bool DoInit(const ReaderInfo& info, int arg_num_fields, const threading::Field* const* arg_fields) override;
+	bool DoInit(const ReaderInfo& info, int arg_num_fields, const zeek::threading::Field* const* arg_fields) override;
 	void DoClose() override;
 	bool DoUpdate() override;
 	bool DoHeartbeat(double network_time, double current_time) override { return true; }
@@ -29,7 +29,7 @@ protected:
 private:
 	bool checkError(int code);
 
-	threading::Value* EntryToVal(sqlite3_stmt *st, const threading::Field *field, int pos, int subpos);
+	zeek::threading::Value* EntryToVal(sqlite3_stmt *st, const zeek::threading::Field *field, int pos, int subpos);
 
 	const threading::Field* const * fields; // raw mapping
 	unsigned int num_fields;
@@ -38,7 +38,7 @@ private:
 	std::string query;
 	sqlite3 *db;
 	sqlite3_stmt *st;
-	threading::formatter::Ascii* io;
+	zeek::threading::formatter::Ascii* io;
 
 	std::string set_separator;
 	std::string unset_field;
diff --git a/src/logging/WriterBackend.cc b/src/logging/WriterBackend.cc
index 336bc59d75..d006b9fcfd 100644
--- a/src/logging/WriterBackend.cc
+++ b/src/logging/WriterBackend.cc
@@ -11,8 +11,8 @@
 
 // Messages sent from backend to frontend (i.e., "OutputMessages").
 
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::logging {
 
diff --git a/src/logging/WriterFrontend.cc b/src/logging/WriterFrontend.cc
index 129507c5e6..c3de094b1f 100644
--- a/src/logging/WriterFrontend.cc
+++ b/src/logging/WriterFrontend.cc
@@ -7,18 +7,18 @@
 #include "WriterFrontend.h"
 #include "WriterBackend.h"
 
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::logging  {
 
 // Messages sent from frontend to backend (i.e., "InputMessages").
 
-class InitMessage final : public threading::InputMessage<WriterBackend>
+class InitMessage final : public zeek::threading::InputMessage<WriterBackend>
 {
 public:
 	InitMessage(WriterBackend* backend, const int num_fields, const Field* const* fields)
-		: threading::InputMessage<WriterBackend>("Init", backend),
+		: zeek::threading::InputMessage<WriterBackend>("Init", backend),
 		num_fields(num_fields), fields(fields)
 			{}
 
@@ -29,12 +29,12 @@ private:
 	const Field * const* fields;
 };
 
-class RotateMessage final : public threading::InputMessage<WriterBackend>
+class RotateMessage final : public zeek::threading::InputMessage<WriterBackend>
 {
 public:
 	RotateMessage(WriterBackend* backend, WriterFrontend* frontend, const char* rotated_path, const double open,
-		      const double close, const bool terminating)
-		: threading::InputMessage<WriterBackend>("Rotate", backend),
+	              const double close, const bool terminating)
+		: zeek::threading::InputMessage<WriterBackend>("Rotate", backend),
 		frontend(frontend),
 		rotated_path(copy_string(rotated_path)), open(open),
 		close(close), terminating(terminating) { }
@@ -51,11 +51,11 @@ private:
 	const bool terminating;
 };
 
-class WriteMessage final : public threading::InputMessage<WriterBackend>
+class WriteMessage final : public zeek::threading::InputMessage<WriterBackend>
 {
 public:
 	WriteMessage(WriterBackend* backend, int num_fields, int num_writes, Value*** vals)
-		: threading::InputMessage<WriterBackend>("Write", backend),
+		: zeek::threading::InputMessage<WriterBackend>("Write", backend),
 		num_fields(num_fields), num_writes(num_writes), vals(vals)	{}
 
 	bool Process() override { return Object()->Write(num_fields, num_writes, vals); }
@@ -66,11 +66,11 @@ private:
 	Value ***vals;
 };
 
-class SetBufMessage final : public threading::InputMessage<WriterBackend>
+class SetBufMessage final : public zeek::threading::InputMessage<WriterBackend>
 {
 public:
 	SetBufMessage(WriterBackend* backend, const bool enabled)
-		: threading::InputMessage<WriterBackend>("SetBuf", backend),
+		: zeek::threading::InputMessage<WriterBackend>("SetBuf", backend),
 		enabled(enabled) { }
 
 	bool Process() override { return Object()->SetBuf(enabled); }
@@ -79,11 +79,11 @@ private:
 	const bool enabled;
 };
 
-class FlushMessage final : public threading::InputMessage<WriterBackend>
+class FlushMessage final : public zeek::threading::InputMessage<WriterBackend>
 {
 public:
 	FlushMessage(WriterBackend* backend, double network_time)
-		: threading::InputMessage<WriterBackend>("Flush", backend),
+		: zeek::threading::InputMessage<WriterBackend>("Flush", backend),
 		network_time(network_time) {}
 
 	bool Process() override { return Object()->Flush(network_time); }
diff --git a/src/logging/writers/ascii/Ascii.cc b/src/logging/writers/ascii/Ascii.cc
index 991efd2599..d92160a478 100644
--- a/src/logging/writers/ascii/Ascii.cc
+++ b/src/logging/writers/ascii/Ascii.cc
@@ -23,9 +23,8 @@
 #include "ascii.bif.h"
 
 using namespace std;
-using namespace threading;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 static constexpr auto shadow_file_prefix = ".shadow.";
 
@@ -359,22 +358,22 @@ bool Ascii::InitFormatter()
 
 	if ( use_json )
 		{
-		formatter::JSON::TimeFormat tf = formatter::JSON::TS_EPOCH;
+		zeek::threading::formatter::JSON::TimeFormat tf = zeek::threading::formatter::JSON::TS_EPOCH;
 
 		// Write out JSON formatted logs.
 		if ( strcmp(json_timestamps.c_str(), "JSON::TS_EPOCH") == 0 )
-			tf = formatter::JSON::TS_EPOCH;
+			tf = zeek::threading::formatter::JSON::TS_EPOCH;
 		else if ( strcmp(json_timestamps.c_str(), "JSON::TS_MILLIS") == 0 )
-			tf = formatter::JSON::TS_MILLIS;
+			tf = zeek::threading::formatter::JSON::TS_MILLIS;
 		else if ( strcmp(json_timestamps.c_str(), "JSON::TS_ISO8601") == 0 )
-			tf = formatter::JSON::TS_ISO8601;
+			tf = zeek::threading::formatter::JSON::TS_ISO8601;
 		else
 			{
 			Error(Fmt("Invalid JSON timestamp format: %s", json_timestamps.c_str()));
 			return false;
 			}
 
-		formatter = new formatter::JSON(this, tf);
+		formatter = new zeek::threading::formatter::JSON(this, tf);
 		// Using JSON implicitly turns off the header meta fields.
 		include_meta = false;
 		}
@@ -387,8 +386,8 @@ bool Ascii::InitFormatter()
 		// Use the default "Bro logs" format.
 		desc.EnableEscaping();
 		desc.AddEscapeSequence(separator);
-		formatter::Ascii::SeparatorInfo sep_info(separator, set_separator, unset_field, empty_field);
-		formatter = new formatter::Ascii(this, sep_info);
+		zeek::threading::formatter::Ascii::SeparatorInfo sep_info(separator, set_separator, unset_field, empty_field);
+		formatter = new zeek::threading::formatter::Ascii(this, sep_info);
 		}
 
 	return true;
@@ -424,7 +423,7 @@ void Ascii::CloseFile(double t)
 	gzfile = nullptr;
 	}
 
-bool Ascii::DoInit(const WriterInfo& info, int num_fields, const Field* const * fields)
+bool Ascii::DoInit(const WriterInfo& info, int num_fields, const zeek::threading::Field* const * fields)
 	{
 	assert(! fd);
 
@@ -596,8 +595,8 @@ bool Ascii::DoFinish(double network_time)
 	return true;
 	}
 
-bool Ascii::DoWrite(int num_fields, const Field* const * fields,
-			     Value** vals)
+bool Ascii::DoWrite(int num_fields, const zeek::threading::Field* const * fields,
+                    zeek::threading::Value** vals)
 	{
 	if ( ! fd )
 		DoInit(Info(), NumFields(), Fields());
diff --git a/src/logging/writers/ascii/Ascii.h b/src/logging/writers/ascii/Ascii.h
index 547770a516..735236d32f 100644
--- a/src/logging/writers/ascii/Ascii.h
+++ b/src/logging/writers/ascii/Ascii.h
@@ -26,9 +26,9 @@ public:
 
 protected:
 	bool DoInit(const WriterInfo& info, int num_fields,
-			    const threading::Field* const* fields) override;
-	bool DoWrite(int num_fields, const threading::Field* const* fields,
-			     threading::Value** vals) override;
+	            const zeek::threading::Field* const* fields) override;
+	bool DoWrite(int num_fields, const zeek::threading::Field* const* fields,
+			     zeek::threading::Value** vals) override;
 	bool DoSetBuf(bool enabled) override;
 	bool DoRotate(const char* rotated_path, double open,
 			      double close, bool terminating) override;
@@ -75,7 +75,7 @@ private:
 	bool enable_utf_8;
 	std::string json_timestamps;
 
-	threading::formatter::Formatter* formatter;
+	zeek::threading::Formatter* formatter;
 	bool init_options;
 };
 
diff --git a/src/logging/writers/sqlite/SQLite.cc b/src/logging/writers/sqlite/SQLite.cc
index ebfb18bf53..6ced41bf6b 100644
--- a/src/logging/writers/sqlite/SQLite.cc
+++ b/src/logging/writers/sqlite/SQLite.cc
@@ -12,8 +12,8 @@
 #include "sqlite.bif.h"
 
 using namespace std;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
 
 namespace zeek::logging::writer::detail {
 
@@ -36,8 +36,8 @@ SQLite::SQLite(zeek::logging::WriterFrontend* frontend)
 			zeek::BifConst::LogSQLite::empty_field->Len()
 			);
 
-	threading::formatter::Ascii::SeparatorInfo sep_info(string(), set_separator, unset_field, empty_field);
-	io = new threading::formatter::Ascii(this, sep_info);
+	zeek::threading::formatter::Ascii::SeparatorInfo sep_info(string(), set_separator, unset_field, empty_field);
+	io = new zeek::threading::formatter::Ascii(this, sep_info);
 	}
 
 SQLite::~SQLite()
diff --git a/src/logging/writers/sqlite/SQLite.h b/src/logging/writers/sqlite/SQLite.h
index 856a4a6388..0902195eac 100644
--- a/src/logging/writers/sqlite/SQLite.h
+++ b/src/logging/writers/sqlite/SQLite.h
@@ -49,7 +49,7 @@ private:
 	std::string unset_field;
 	std::string empty_field;
 
-	threading::formatter::Ascii* io;
+	zeek::threading::formatter::Ascii* io;
 };
 
 } // namespace zeek::logging::writer::detail
diff --git a/src/plugin/Plugin.h b/src/plugin/Plugin.h
index 84d1d276b8..902a59e5a5 100644
--- a/src/plugin/Plugin.h
+++ b/src/plugin/Plugin.h
@@ -21,6 +21,13 @@ ZEEK_FORWARD_DECLARE_NAMESPACED(Event, zeek);
 ZEEK_FORWARD_DECLARE_NAMESPACED(Func, zeek);
 ZEEK_FORWARD_DECLARE_NAMESPACED(Frame, zeek::detail);
 
+namespace zeek::threading {
+	struct Field;
+}
+namespace threading {
+	using Field [[deprecated("Remove in v4.1. Use zeek::threading::Field.")]] = zeek::threading::Field;
+}
+
 namespace zeek {
 template <class T> class IntrusivePtr;
 using ValPtr = zeek::IntrusivePtr<Val>;
@@ -29,10 +36,6 @@ class Obj;
 
 using BroObj [[deprecated("Remove in v4.1. Use zeek::Obj instead.")]] = zeek::Obj;
 
-namespace threading {
-struct Field;
-}
-
 namespace zeek::plugin  {
 
 class Manager;
diff --git a/src/stats.bif b/src/stats.bif
index 7042d86d3f..0908e3b427 100644
--- a/src/stats.bif
+++ b/src/stats.bif
@@ -339,7 +339,7 @@ function get_thread_stats%(%): ThreadStats
 	auto r = zeek::make_intrusive<zeek::RecordVal>(ThreadStats);
 	int n = 0;
 
-	r->Assign(n++, zeek::val_mgr->Count(thread_mgr->NumThreads()));
+	r->Assign(n++, zeek::val_mgr->Count(zeek::thread_mgr->NumThreads()));
 
 	return r;
 	%}
diff --git a/src/threading/BasicThread.cc b/src/threading/BasicThread.cc
index c6bc01f39c..9228603c66 100644
--- a/src/threading/BasicThread.cc
+++ b/src/threading/BasicThread.cc
@@ -7,7 +7,7 @@
 #include "Manager.h"
 #include "util.h"
 
-using namespace threading;
+namespace zeek::threading {
 
 static const int STD_FMT_BUF_LEN = 2048;
 
@@ -193,3 +193,5 @@ void* BasicThread::launcher(void *arg)
 
 	return nullptr;
 	}
+
+} // namespace zeek::threading
diff --git a/src/threading/BasicThread.h b/src/threading/BasicThread.h
index fa65e070ee..04dc05e621 100644
--- a/src/threading/BasicThread.h
+++ b/src/threading/BasicThread.h
@@ -1,14 +1,16 @@
 
 #pragma once
 
+#include "zeek-config.h"
+
 #include <stdint.h>
 
 #include <iosfwd>
 #include <thread>
 
-namespace threading {
+ZEEK_FORWARD_DECLARE_NAMESPACED(Manager, zeek, threading);
 
-class Manager;
+namespace zeek::threading {
 
 /**
  * Base class for all threads.
@@ -211,4 +213,8 @@ private:
 	static uint64_t thread_counter;
 };
 
+} // namespace zeek::threading
+
+namespace threading {
+	using BasicThread [[deprecated("Remove in v4.1. Use zeek::threading::BasicThread.")]] = zeek::threading::BasicThread;
 }
diff --git a/src/threading/Formatter.cc b/src/threading/Formatter.cc
index b5b0643676..ad454ae1d6 100644
--- a/src/threading/Formatter.cc
+++ b/src/threading/Formatter.cc
@@ -8,10 +8,10 @@
 #include "MsgThread.h"
 #include "bro_inet_ntop.h"
 
-using namespace threading;
-using namespace formatter;
-using threading::Value;
-using threading::Field;
+using zeek::threading::Value;
+using zeek::threading::Field;
+
+namespace zeek::threading {
 
 Formatter::Formatter(threading::MsgThread* t)
 	{
@@ -125,3 +125,5 @@ std::string Formatter::Render(TransportProto proto)
 	else
 		return "unknown";
 	}
+
+} // namespace zeek::threading::formatter
diff --git a/src/threading/Formatter.h b/src/threading/Formatter.h
index dc834ccd81..a1ba38ceaf 100644
--- a/src/threading/Formatter.h
+++ b/src/threading/Formatter.h
@@ -7,11 +7,9 @@
 #include "Type.h"
 #include "SerialTypes.h"
 
-namespace threading {
+ZEEK_FORWARD_DECLARE_NAMESPACED(MsgThread, zeek, threading);
 
-class MsgThread;
-
-namespace formatter {
+namespace zeek::threading {
 
 /**
   * A thread-safe class for converting values into some textual format. This
@@ -164,4 +162,8 @@ private:
 	threading::MsgThread* thread;
 };
 
-}}
+} // zeek::threading
+
+namespace threading::formatter {
+	using Formatter [[deprecated("Remove in v4.1. Use zeek::threading::Formatter.")]] = zeek::threading::Formatter;
+}
diff --git a/src/threading/Manager.cc b/src/threading/Manager.cc
index 8591006723..d5604668d3 100644
--- a/src/threading/Manager.cc
+++ b/src/threading/Manager.cc
@@ -8,7 +8,8 @@
 #include "Event.h"
 #include "IPAddr.h"
 
-using namespace threading;
+namespace zeek::threading {
+namespace detail {
 
 void HeartbeatTimer::Dispatch(double t, bool is_expire)
 	{
@@ -19,6 +20,8 @@ void HeartbeatTimer::Dispatch(double t, bool is_expire)
 	thread_mgr->StartHeartbeatTimer();
 	}
 
+} // namespace detail
+
 Manager::Manager()
 	{
 	DBG_LOG(zeek::DBG_THREADING, "Creating thread manager ...");
@@ -127,7 +130,7 @@ void Manager::SendHeartbeats()
 void Manager::StartHeartbeatTimer()
 	{
 	heartbeat_timer_running = true;
-	zeek::detail::timer_mgr->Add(new HeartbeatTimer(network_time + zeek::BifConst::Threading::heartbeat_interval));
+	zeek::detail::timer_mgr->Add(new detail::HeartbeatTimer(network_time + zeek::BifConst::Threading::heartbeat_interval));
 	}
 
 // Raise everything in here as warnings so it is passed to scriptland without
@@ -269,3 +272,5 @@ const threading::Manager::msg_stats_list& threading::Manager::GetMsgThreadStats(
 
 	return stats;
 	}
+
+} // namespace zeek::threading
diff --git a/src/threading/Manager.h b/src/threading/Manager.h
index 443473954d..ccfd5c8e10 100644
--- a/src/threading/Manager.h
+++ b/src/threading/Manager.h
@@ -7,7 +7,9 @@
 #include <list>
 #include <utility>
 
+namespace zeek {
 namespace threading {
+namespace detail {
 
 class HeartbeatTimer final : public zeek::detail::Timer {
 public:
@@ -21,6 +23,8 @@ protected:
 	void Init();
 };
 
+} // namespace detail
+
 /**
  * The thread manager coordinates all child threads. Once a BasicThread is
  * instantitated, it gets addedd to the manager, which will delete it later
@@ -103,7 +107,7 @@ public:
 protected:
 	friend class BasicThread;
 	friend class MsgThread;
-	friend class HeartbeatTimer;
+	friend class detail::HeartbeatTimer;
 
 	/**
 	 * Registers a new basic thread with the manager. This is
@@ -151,10 +155,21 @@ private:
 	bool heartbeat_timer_running = false;
 };
 
-}
+} // namespace threading
 
 /**
  * A singleton instance of the thread manager. All methods must only be
- * called from Bro's main thread.
+ * called from Zeek's main thread.
  */
 extern threading::Manager* thread_mgr;
+
+} // namespace zeek
+
+extern zeek::threading::Manager*& thread_mgr [[deprecated("Remove in v4.1. Use zeek::thread_mgr.")]];
+
+namespace threading::detail {
+	using HeartbeatTimer [[deprecated("Remove in v4.1. Use zeek::threading::detail::HeartbeatTimer.")]] = zeek::threading::detail::HeartbeatTimer;
+}
+namespace threading {
+	using Manager [[deprecated("Remove in v4.1. Use zeek::threading::Manager.")]] = zeek::threading::Manager;
+}
diff --git a/src/threading/MsgThread.cc b/src/threading/MsgThread.cc
index 2c12dc3b05..dac9254adf 100644
--- a/src/threading/MsgThread.cc
+++ b/src/threading/MsgThread.cc
@@ -8,9 +8,11 @@
 #include "Manager.h"
 #include "iosource/Manager.h"
 
-using namespace threading;
+// Set by Zeek's main signal handler.
+extern int signal_val;
 
-namespace threading  {
+namespace zeek::threading {
+namespace detail {
 
 ////// Messages.
 
@@ -124,8 +126,6 @@ private:
 };
 #endif
 
-}
-
 // An event that the child wants to pass into the main event queue
 class SendEventMessage final : public OutputMessage<MsgThread> {
 public:
@@ -151,13 +151,6 @@ private:
 	Value* *val;
 };
 
-////// Methods.
-
-Message::~Message()
-	{
-	delete [] name;
-	}
-
 bool ReporterMessage::Process()
 	{
 	switch ( type ) {
@@ -197,6 +190,15 @@ bool ReporterMessage::Process()
 	return true;
 	}
 
+} // namespace detail
+
+////// Methods.
+
+Message::~Message()
+	{
+	delete [] name;
+	}
+
 MsgThread::MsgThread() : BasicThread(), queue_in(this, nullptr), queue_out(nullptr, this)
 	{
 	cnt_sent_in = cnt_sent_out = 0;
@@ -219,9 +221,6 @@ MsgThread::~MsgThread()
 	zeek::iosource_mgr->UnregisterFd(flare.FD(), this);
 	}
 
-// Set by Bro's main signal handler.
-extern int signal_val;
-
 void MsgThread::OnSignalStop()
 	{
 	if ( main_finished || Killed() || child_sent_finish )
@@ -229,7 +228,7 @@ void MsgThread::OnSignalStop()
 
 	child_sent_finish = true;
 	// Signal thread to terminate.
-	SendIn(new FinishMessage(this, network_time), true);
+	SendIn(new detail::FinishMessage(this, network_time), true);
 	}
 
 void MsgThread::OnWaitForStop()
@@ -303,43 +302,43 @@ void MsgThread::Heartbeat()
 	if ( child_sent_finish )
 		return;
 
-	SendIn(new HeartbeatMessage(this, network_time, current_time()));
+	SendIn(new detail::HeartbeatMessage(this, network_time, current_time()));
 	}
 
 void MsgThread::Finished()
 	{
 	child_finished = true;
-	SendOut(new FinishedMessage(this));
+	SendOut(new detail::FinishedMessage(this));
 	}
 
 void MsgThread::Info(const char* msg)
 	{
-	SendOut(new ReporterMessage(ReporterMessage::INFO, this, msg));
+	SendOut(new detail::ReporterMessage(detail::ReporterMessage::INFO, this, msg));
 	}
 
 void MsgThread::Warning(const char* msg)
 	{
-	SendOut(new ReporterMessage(ReporterMessage::WARNING, this, msg));
+	SendOut(new detail::ReporterMessage(detail::ReporterMessage::WARNING, this, msg));
 	}
 
 void MsgThread::Error(const char* msg)
 	{
-	SendOut(new ReporterMessage(ReporterMessage::ERROR, this, msg));
+	SendOut(new detail::ReporterMessage(detail::ReporterMessage::ERROR, this, msg));
 	}
 
 void MsgThread::FatalError(const char* msg)
 	{
-	SendOut(new ReporterMessage(ReporterMessage::FATAL_ERROR, this, msg));
+	SendOut(new detail::ReporterMessage(detail::ReporterMessage::FATAL_ERROR, this, msg));
 	}
 
 void MsgThread::FatalErrorWithCore(const char* msg)
 	{
-	SendOut(new ReporterMessage(ReporterMessage::FATAL_ERROR_WITH_CORE, this, msg));
+	SendOut(new detail::ReporterMessage(detail::ReporterMessage::FATAL_ERROR_WITH_CORE, this, msg));
 	}
 
 void MsgThread::InternalWarning(const char* msg)
 	{
-	SendOut(new ReporterMessage(ReporterMessage::INTERNAL_WARNING, this, msg));
+	SendOut(new detail::ReporterMessage(detail::ReporterMessage::INTERNAL_WARNING, this, msg));
 	}
 
 void MsgThread::InternalError(const char* msg)
@@ -353,7 +352,7 @@ void MsgThread::InternalError(const char* msg)
 
 void MsgThread::Debug(zeek::DebugStream stream, const char* msg)
 	{
-	SendOut(new DebugMessage(stream, this, msg));
+	SendOut(new detail::DebugMessage(stream, this, msg));
 	}
 
 #endif
@@ -390,7 +389,7 @@ void MsgThread::SendOut(BasicOutputMessage* msg, bool force)
 
 void MsgThread::SendEvent(const char* name, const int num_vals, Value* *vals)
 	{
-	SendOut(new SendEventMessage(this, name, num_vals, vals));
+	SendOut(new detail::SendEventMessage(this, name, num_vals, vals));
 	}
 
 BasicOutputMessage* MsgThread::RetrieveOut()
@@ -440,7 +439,7 @@ void MsgThread::Run()
 			// after all other outgoing messages (in particular
 			// error messages have been processed by then main
 			// thread).
-			SendOut(new KillMeMessage(this));
+			SendOut(new detail::KillMeMessage(this));
 			failed = true;
 			}
 		}
@@ -483,3 +482,5 @@ void MsgThread::Process()
 		delete msg;
 		}
 	}
+
+} // namespace zeek::threading
diff --git a/src/threading/MsgThread.h b/src/threading/MsgThread.h
index f62abfea03..6c2505986a 100644
--- a/src/threading/MsgThread.h
+++ b/src/threading/MsgThread.h
@@ -8,13 +8,29 @@
 #include "iosource/IOSource.h"
 #include "Flare.h"
 
+namespace zeek::threading {
+	struct Value;
+	struct Field;
+}
 namespace threading {
+	using Value [[deprecated("Remove in v4.1. Use zeek::threading::Value.")]] = zeek::threading::Value;
+	using Field [[deprecated("Remove in v4.1. Use zeek::threading::Field.")]] = zeek::threading::Field;
+}
+
+namespace zeek::threading {
 
 class BasicInputMessage;
 class BasicOutputMessage;
+
+namespace detail {
+
+// These classes are marked as friends later so they need to be forward declared.
 class HeartbeatMessage;
-struct Value;
-struct Field;
+class FinishMessage;
+class FinishedMessage;
+class KillMeMessage;
+
+}
 
 /**
  * A specialized thread that provides bi-directional message passing between
@@ -205,10 +221,10 @@ public:
 
 protected:
 	friend class Manager;
-	friend class HeartbeatMessage;
-	friend class FinishMessage;
-	friend class FinishedMessage;
-	friend class KillMeMessage;
+	friend class detail::HeartbeatMessage;
+	friend class detail::FinishMessage;
+	friend class detail::FinishedMessage;
+	friend class detail::KillMeMessage;
 
 	/**
 	 * Pops a message sent by the child from the child-to-main queue.
@@ -464,4 +480,13 @@ private:
 	O* object;
 };
 
-}
+} // namespace zeek::threading
+
+namespace threading {
+	using MsgThread [[deprecated("Remove in v4.1. Use zeek::threading::MsgThread.")]] = zeek::threading::MsgThread;
+	using Message [[deprecated("Remove in v4.1. Use zeek::threading::Message.")]] = zeek::threading::Message;
+	using BasicInputMessage [[deprecated("Remove in v4.1. Use zeek::threading::BasicInputMessage.")]] = zeek::threading::BasicInputMessage;
+	using BasicOutputMessage [[deprecated("Remove in v4.1. Use zeek::threading::BasicOutputMessage.")]] = zeek::threading::BasicOutputMessage;
+	template<typename O> using InputMessage [[deprecated("Remove in v4.1. Use zeek::threading::InputMessage.")]] = zeek::threading::InputMessage<O>;
+	template<typename O> using OutputMessage [[deprecated("Remove in v4.1. Use zeek::threading::OutputMessage.")]] = zeek::threading::OutputMessage<O>;
+} // namespace threading
diff --git a/src/threading/Queue.h b/src/threading/Queue.h
index 1840540ac6..5a261bfa47 100644
--- a/src/threading/Queue.h
+++ b/src/threading/Queue.h
@@ -12,7 +12,7 @@
 
 #undef Queue // Defined elsewhere unfortunately.
 
-namespace threading {
+namespace zeek::threading {
 
 /**
  * A thread-safe single-reader single-writer queue.
@@ -261,4 +261,8 @@ inline void Queue<T>::WakeUp()
 		}
 	}
 
+} // namespace zeek::threading
+
+namespace threading {
+	template<typename T> using Queue [[deprecated("Remove in v4.1. Use zeek::threading::Queue.")]] = zeek::threading::Queue<T>;
 }
diff --git a/src/threading/SerialTypes.cc b/src/threading/SerialTypes.cc
index 97e3d055f3..633ecf5007 100644
--- a/src/threading/SerialTypes.cc
+++ b/src/threading/SerialTypes.cc
@@ -14,7 +14,7 @@
 #include "Scope.h"
 #include "IPAddr.h"
 
-using namespace threading;
+namespace zeek::threading {
 
 bool Field::Read(zeek::detail::SerializationFormat* fmt)
 	{
@@ -636,3 +636,5 @@ zeek::Val* Value::ValueToVal(const std::string& source, const Value* val, bool&
 	assert(false);
 	return nullptr;
 	}
+
+} // namespace zeek::threading
diff --git a/src/threading/SerialTypes.h b/src/threading/SerialTypes.h
index e1c5c886e2..641513e341 100644
--- a/src/threading/SerialTypes.h
+++ b/src/threading/SerialTypes.h
@@ -11,7 +11,7 @@
 
 ZEEK_FORWARD_DECLARE_NAMESPACED(SerializationFormat, zeek::detail);
 
-namespace threading {
+namespace zeek::threading {
 
 /**
  * Definition of a log file, i.e., one column of a log stream.
@@ -214,4 +214,9 @@ private:
 	Value(const Value& other) = delete;
 };
 
+} // namespace zeek::threading
+
+namespace threading {
+	using Field [[deprecated("Remove in v4.1. Use zeek::threading::Field.")]] = zeek::threading::Field;
+	using Value [[deprecated("Remove in v4.1. Use zeek::threading::Value.")]] = zeek::threading::Value;
 }
diff --git a/src/threading/formatters/Ascii.cc b/src/threading/formatters/Ascii.cc
index f171d0b467..73a292c6f1 100644
--- a/src/threading/formatters/Ascii.cc
+++ b/src/threading/formatters/Ascii.cc
@@ -10,7 +10,8 @@
 #include <errno.h>
 
 using namespace std;
-using namespace threading::formatter;
+
+namespace zeek::threading::formatter {
 
 // If the value we'd write out would match exactly the a reserved string, we
 // escape the first character so that the output won't be ambigious. If this
@@ -47,7 +48,7 @@ Ascii::SeparatorInfo::SeparatorInfo(const string& arg_separator,
 	empty_field = arg_empty_field;
 	}
 
-Ascii::Ascii(threading::MsgThread* t, const SeparatorInfo& info) : Formatter(t)
+Ascii::Ascii(zeek::threading::MsgThread* t, const SeparatorInfo& info) : zeek::threading::Formatter(t)
 	{
 	separators = info;
 	}
@@ -56,8 +57,8 @@ Ascii::~Ascii()
 	{
 	}
 
-bool Ascii::Describe(zeek::ODesc* desc, int num_fields, const threading::Field* const * fields,
-                     threading::Value** vals) const
+bool Ascii::Describe(zeek::ODesc* desc, int num_fields, const zeek::threading::Field* const * fields,
+                     zeek::threading::Value** vals) const
 	{
 	for ( int i = 0; i < num_fields; i++ )
 		{
@@ -71,7 +72,7 @@ bool Ascii::Describe(zeek::ODesc* desc, int num_fields, const threading::Field*
 	return true;
 	}
 
-bool Ascii::Describe(zeek::ODesc* desc, threading::Value* val, const string& name) const
+bool Ascii::Describe(zeek::ODesc* desc, zeek::threading::Value* val, const string& name) const
 	{
 	if ( ! val->present )
 		{
@@ -207,12 +208,12 @@ bool Ascii::Describe(zeek::ODesc* desc, threading::Value* val, const string& nam
 	}
 
 
-threading::Value* Ascii::ParseValue(const string& s, const string& name, zeek::TypeTag type, zeek::TypeTag subtype) const
+zeek::threading::Value* Ascii::ParseValue(const string& s, const string& name, zeek::TypeTag type, zeek::TypeTag subtype) const
 	{
 	if ( ! separators.unset_field.empty() && s.compare(separators.unset_field) == 0 )  // field is not set...
-		return new threading::Value(type, false);
+		return new zeek::threading::Value(type, false);
 
-	threading::Value* val = new threading::Value(type, subtype, true);
+	zeek::threading::Value* val = new zeek::threading::Value(type, subtype, true);
 	const char* start = s.c_str();
 	char* end = nullptr;
 	errno = 0;
@@ -373,7 +374,7 @@ threading::Value* Ascii::ParseValue(const string& s, const string& name, zeek::T
 		if ( separators.empty_field.empty() && s.empty() )
 			length = 0;
 
-		threading::Value** lvals = new threading::Value* [length];
+		zeek::threading::Value** lvals = new zeek::threading::Value* [length];
 
 		if ( type == zeek::TYPE_TABLE )
 			{
@@ -409,7 +410,7 @@ threading::Value* Ascii::ParseValue(const string& s, const string& name, zeek::T
 				break;
 				}
 
-			threading::Value* newval = ParseValue(element, name, subtype);
+			zeek::threading::Value* newval = ParseValue(element, name, subtype);
 			if ( newval == nullptr )
 				{
 				GetThread()->Warning("Error while reading set or vector");
@@ -474,7 +475,7 @@ parse_error:
 
 bool Ascii::CheckNumberError(const char* start, const char* end) const
 	{
-	threading::MsgThread* thread = GetThread();
+	zeek::threading::MsgThread* thread = GetThread();
 
 	if ( end == start && *end != '\0'  ) {
 		thread->Warning(thread->Fmt("String '%s' contained no parseable number", start));
@@ -504,3 +505,5 @@ bool Ascii::CheckNumberError(const char* start, const char* end) const
 
 	return false;
 	}
+
+} // namespace zeek::threading::formatter
diff --git a/src/threading/formatters/Ascii.h b/src/threading/formatters/Ascii.h
index b010e29b90..90b7e303d2 100644
--- a/src/threading/formatters/Ascii.h
+++ b/src/threading/formatters/Ascii.h
@@ -4,9 +4,9 @@
 
 #include "../Formatter.h"
 
-namespace threading { namespace formatter {
+namespace zeek::threading::formatter {
 
-class Ascii final : public Formatter {
+class Ascii final : public zeek::threading::Formatter {
 public:
 	/**
 	 * A struct to pass the necessary configuration values to the
@@ -44,14 +44,14 @@ public:
 	 * @param info SeparatorInfo structure defining the necessary
 	 * separators.
 	 */
-	Ascii(threading::MsgThread* t, const SeparatorInfo& info);
+	Ascii(zeek::threading::MsgThread* t, const SeparatorInfo& info);
 	virtual ~Ascii();
 
-	virtual bool Describe(zeek::ODesc* desc, threading::Value* val, const std::string& name = "") const;
-	virtual bool Describe(zeek::ODesc* desc, int num_fields, const threading::Field* const * fields,
-	                      threading::Value** vals) const;
-	virtual threading::Value* ParseValue(const std::string& s, const std::string& name,
-		                                 zeek::TypeTag type, zeek::TypeTag subtype = zeek::TYPE_ERROR) const;
+	virtual bool Describe(zeek::ODesc* desc, zeek::threading::Value* val, const std::string& name = "") const;
+	virtual bool Describe(zeek::ODesc* desc, int num_fields, const zeek::threading::Field* const * fields,
+	                      zeek::threading::Value** vals) const;
+	virtual zeek::threading::Value* ParseValue(const std::string& s, const std::string& name,
+	                                           zeek::TypeTag type, zeek::TypeTag subtype = zeek::TYPE_ERROR) const;
 
 private:
 	bool CheckNumberError(const char* start, const char* end) const;
@@ -59,4 +59,8 @@ private:
 	SeparatorInfo separators;
 };
 
-}}
+} // namespace zeek::threading::formatter
+
+namespace threading::formatter {
+	using Ascii [[deprecated("Remove in v4.1. Use zeek::threading::formatter::Ascii.")]] = zeek::threading::formatter::Ascii;
+}
diff --git a/src/threading/formatters/JSON.cc b/src/threading/formatters/JSON.cc
index e7563d78b5..bea46700ba 100644
--- a/src/threading/formatters/JSON.cc
+++ b/src/threading/formatters/JSON.cc
@@ -16,7 +16,7 @@
 #include <math.h>
 #include <stdint.h>
 
-using namespace threading::formatter;
+namespace zeek::threading::formatter {
 
 bool JSON::NullDoubleWriter::Double(double d)
 	{
@@ -26,7 +26,7 @@ bool JSON::NullDoubleWriter::Double(double d)
 	return rapidjson::Writer<rapidjson::StringBuffer>::Double(d);
 	}
 
-JSON::JSON(MsgThread* t, TimeFormat tf) : Formatter(t), surrounding_braces(true)
+JSON::JSON(zeek::threading::MsgThread* t, TimeFormat tf) : zeek::threading::Formatter(t), surrounding_braces(true)
 	{
 	timestamps = tf;
 	}
@@ -35,8 +35,8 @@ JSON::~JSON()
 	{
 	}
 
-bool JSON::Describe(zeek::ODesc* desc, int num_fields, const Field* const * fields,
-                    Value** vals) const
+bool JSON::Describe(zeek::ODesc* desc, int num_fields, const zeek::threading::Field* const * fields,
+                    zeek::threading::Value** vals) const
 	{
 	rapidjson::StringBuffer buffer;
 	NullDoubleWriter writer(buffer);
@@ -55,7 +55,7 @@ bool JSON::Describe(zeek::ODesc* desc, int num_fields, const Field* const * fiel
 	return true;
 	}
 
-bool JSON::Describe(zeek::ODesc* desc, Value* val, const std::string& name) const
+bool JSON::Describe(zeek::ODesc* desc, zeek::threading::Value* val, const std::string& name) const
 	{
 	if ( desc->IsBinary() )
 		{
@@ -78,13 +78,14 @@ bool JSON::Describe(zeek::ODesc* desc, Value* val, const std::string& name) cons
 	return true;
 	}
 
-threading::Value* JSON::ParseValue(const std::string& s, const std::string& name, zeek::TypeTag type, zeek::TypeTag subtype) const
+zeek::threading::Value* JSON::ParseValue(const std::string& s, const std::string& name,
+                                         zeek::TypeTag type, zeek::TypeTag subtype) const
 	{
 	GetThread()->Error("JSON formatter does not support parsing yet.");
 	return nullptr;
 	}
 
-void JSON::BuildJSON(NullDoubleWriter& writer, Value* val, const std::string& name) const
+void JSON::BuildJSON(NullDoubleWriter& writer, zeek::threading::Value* val, const std::string& name) const
 	{
 	if ( ! val->present )
 		{
@@ -204,3 +205,5 @@ void JSON::BuildJSON(NullDoubleWriter& writer, Value* val, const std::string& na
 			break;
 		}
 	}
+
+} // namespace zeek::threading::formatter
diff --git a/src/threading/formatters/JSON.h b/src/threading/formatters/JSON.h
index a02d8367c6..dd8643d6c6 100644
--- a/src/threading/formatters/JSON.h
+++ b/src/threading/formatters/JSON.h
@@ -8,13 +8,13 @@
 
 #include "../Formatter.h"
 
-namespace threading { namespace formatter {
+namespace zeek::threading::formatter {
 
 /**
   * A thread-safe class for converting values into a JSON representation
   * and vice versa.
   */
-class JSON : public Formatter {
+class JSON : public zeek::threading::Formatter {
 public:
 	enum TimeFormat {
 		TS_EPOCH,	// Doubles that represents seconds from the UNIX epoch.
@@ -22,14 +22,14 @@ public:
 		TS_MILLIS	// Milliseconds from the UNIX epoch.  Some consumers need this (e.g., elasticsearch).
 		};
 
-	JSON(threading::MsgThread* t, TimeFormat tf);
+	JSON(zeek::threading::MsgThread* t, TimeFormat tf);
 	~JSON() override;
 
-	bool Describe(zeek::ODesc* desc, threading::Value* val, const std::string& name = "") const override;
-	bool Describe(zeek::ODesc* desc, int num_fields, const threading::Field* const * fields,
-	              threading::Value** vals) const override;
-	threading::Value* ParseValue(const std::string& s, const std::string& name, zeek::TypeTag type,
-	                             zeek::TypeTag subtype = zeek::TYPE_ERROR) const override;
+	bool Describe(zeek::ODesc* desc, zeek::threading::Value* val, const std::string& name = "") const override;
+	bool Describe(zeek::ODesc* desc, int num_fields, const zeek::threading::Field* const * fields,
+	              zeek::threading::Value** vals) const override;
+	zeek::threading::Value* ParseValue(const std::string& s, const std::string& name, zeek::TypeTag type,
+	                                   zeek::TypeTag subtype = zeek::TYPE_ERROR) const override;
 
 	class NullDoubleWriter : public rapidjson::Writer<rapidjson::StringBuffer> {
 	public:
@@ -38,10 +38,14 @@ public:
 	};
 
 private:
-	void BuildJSON(NullDoubleWriter& writer, Value* val, const std::string& name = "") const;
+	void BuildJSON(NullDoubleWriter& writer, zeek::threading::Value* val, const std::string& name = "") const;
 
 	TimeFormat timestamps;
 	bool surrounding_braces;
 };
 
-}}
+} // namespace zeek::threading::formatter
+
+namespace threading::formatter {
+	using JSON [[deprecated("Remove in v4.1. Use zeek::threading::formatter::JSON.")]] = zeek::threading::formatter::JSON;
+}
diff --git a/src/zeek-setup.cc b/src/zeek-setup.cc
index b20cc25688..17576f712e 100644
--- a/src/zeek-setup.cc
+++ b/src/zeek-setup.cc
@@ -104,7 +104,8 @@ zeek::detail::TimerMgr*& timer_mgr = zeek::detail::timer_mgr;
 
 zeek::logging::Manager* zeek::log_mgr = nullptr;
 zeek::logging::Manager*& log_mgr = zeek::log_mgr;
-threading::Manager* thread_mgr = nullptr;
+zeek::threading::Manager* zeek::thread_mgr = nullptr;
+zeek::threading::Manager*& thread_mgr = zeek::thread_mgr;
 zeek::input::Manager* zeek::input_mgr = nullptr;
 zeek::input::Manager*& input_mgr = zeek::input_mgr;
 zeek::file_analysis::Manager* zeek::file_mgr = nullptr;
@@ -309,7 +310,7 @@ void terminate_bro()
 	notifier::registry.Terminate();
 	zeek::log_mgr->Terminate();
 	zeek::input_mgr->Terminate();
-	thread_mgr->Terminate();
+	zeek::thread_mgr->Terminate();
 	broker_mgr->Terminate();
 	zeek::detail::dns_mgr->Terminate();
 
@@ -485,7 +486,7 @@ zeek::detail::SetupResult zeek::detail::setup(int argc, char** argv,
 
 	zeek::val_mgr = new ValManager();
 	reporter = new Reporter(options.abort_on_scripting_errors);
-	thread_mgr = new threading::Manager();
+	zeek::thread_mgr = new threading::Manager();
 	zeek::plugin_mgr = new zeek::plugin::Manager();
 
 #ifdef DEBUG