diff --git a/src/Anon.h b/src/Anon.h
index a3d7016cb7..3b2e704083 100644
--- a/src/Anon.h
+++ b/src/Anon.h
@@ -13,8 +13,6 @@
 #include <vector>
 #include <map>
 
-using std::map;
-
 // TODO: Anon.h may not be the right place to put these functions ...
 
 enum ip_addr_anonymization_class_t {
@@ -51,7 +49,7 @@ public:
 	bool PreserveNet(ipaddr32_t input);
 
 protected:
-	map<ipaddr32_t, ipaddr32_t> mapping;
+	std::map<ipaddr32_t, ipaddr32_t> mapping;
 };
 
 class AnonymizeIPAddr_Seq : public AnonymizeIPAddr {
diff --git a/src/Base64.h b/src/Base64.h
index cdebc93017..fae0b29a7d 100644
--- a/src/Base64.h
+++ b/src/Base64.h
@@ -2,8 +2,6 @@
 
 #include <string>
 
-using std::string;
-
 class BroString;
 class Connection;
 
@@ -15,7 +13,7 @@ public:
 	// encode_base64()), encoding-errors will go to Reporter instead of
 	// Weird. Usage errors go to Reporter in any case. Empty alphabet
 	// indicates the default base64 alphabet.
-	explicit Base64Converter(Connection* conn, const string& alphabet = "");
+	explicit Base64Converter(Connection* conn, const std::string& alphabet = "");
 	~Base64Converter();
 
 	// A note on Decode():
@@ -44,10 +42,10 @@ protected:
 	char error_msg[256];
 
 protected:
-	static const string default_alphabet;
-	string alphabet;
+	static const std::string default_alphabet;
+	std::string alphabet;
 
-	static int* InitBase64Table(const string& alphabet);
+	static int* InitBase64Table(const std::string& alphabet);
 	static int default_base64_table[256];
 	char base64_group[4];
 	int base64_group_next;
diff --git a/src/Brofiler.h b/src/Brofiler.h
index ee8d528baf..859f777fc3 100644
--- a/src/Brofiler.h
+++ b/src/Brofiler.h
@@ -5,11 +5,6 @@
 #include <list>
 #include <string>
 
-using std::list;
-using std::map;
-using std::pair;
-using std::string;
-
 class Stmt;
 
 /**
@@ -50,7 +45,7 @@ private:
 	/**
 	 * The current, global Brofiler instance creates this list at parse-time.
 	 */
-	list<Stmt*> stmts;
+	std::list<Stmt*> stmts;
 
 	/**
 	 * Indicates whether new statments will not be considered as part of
@@ -64,7 +59,7 @@ private:
 	 * startup time and modified at shutdown time before writing back
 	 * to a file.
 	 */
-	map<pair<string, string>, uint64_t> usage_map;
+	std::map<std::pair<std::string, std::string>, uint64_t> usage_map;
 
 	/**
 	 * The character to use to delimit Brofiler output files.  Default is '\t'.
diff --git a/src/DbgBreakpoint.h b/src/DbgBreakpoint.h
index e27fabe2c1..00683a2aad 100644
--- a/src/DbgBreakpoint.h
+++ b/src/DbgBreakpoint.h
@@ -4,8 +4,6 @@
 
 #include <string>
 
-using std::string;
-
 struct ParseLocationRec;
 class Stmt;
 
@@ -40,8 +38,8 @@ public:
 	BreakCode ShouldBreak(Stmt* s);
 	BreakCode ShouldBreak(double t);
 
-	const string& GetCondition() const	{ return condition; }
-	bool SetCondition(const string& new_condition);
+	const std::string& GetCondition() const	{ return condition; }
+	bool SetCondition(const std::string& new_condition);
 
 	int GetRepeatCount() const	{ return repeat_count; }
 	bool SetRepeatCount(int count); // implements function of ignore command in gdb
@@ -68,7 +66,7 @@ protected:
 	int BPID;
 
 	char description[512];
-	string function_name;	// location
+	std::string function_name;	// location
 	const char* source_filename;
 	int source_line;
 
@@ -79,5 +77,5 @@ protected:
 	int repeat_count;	// if positive, break after this many hits
 	int hit_count;	// how many times it's been hit (w/o breaking)
 
-	string condition;	// condition to evaluate; nil for none
+	std::string condition;	// condition to evaluate; nil for none
 };