diff --git a/src/ID.h b/src/ID.h
index a1cbe494d3..9c9a842c39 100644
--- a/src/ID.h
+++ b/src/ID.h
@@ -70,10 +70,6 @@ public:
 
 	bool IsRedefinable() const	{ return FindAttr(ATTR_REDEF) != 0; }
 
-	// Returns true if ID is one of those internal globally unique IDs
-	// to which MutableVals are bound (there name start with a '#').
-	bool IsInternalGlobal() const	{ return name && name[0] == '#'; }
-
 	void SetAttrs(Attributes* attr);
 	void AddAttrs(Attributes* attr);
 	void RemoveAttr(attr_tag a);
diff --git a/src/StateAccess.cc b/src/StateAccess.cc
index 7d7c397981..b580215271 100644
--- a/src/StateAccess.cc
+++ b/src/StateAccess.cc
@@ -14,8 +14,8 @@ notifier::Registry::~Registry()
 
 void notifier::Registry::Register(Modifiable* m, notifier::Notifier* notifier)
 	{
-	DBG_LOG(DBG_NOTIFIERS, "registering modifiable %p for notifier %s",
-		m, notifier->Name());
+	DBG_LOG(DBG_NOTIFIERS, "registering modifiable %p for notifier %p",
+		m, notifier);
 
 	registrations.insert({m, notifier});
 	++m->notifiers;
@@ -23,16 +23,16 @@ void notifier::Registry::Register(Modifiable* m, notifier::Notifier* notifier)
 
 void notifier::Registry::Unregister(Modifiable* m, notifier::Notifier* notifier)
 	{
-	DBG_LOG(DBG_NOTIFIERS, "unregistering modifiable %p from notifier %s",
-		m, notifier->Name());
+	DBG_LOG(DBG_NOTIFIERS, "unregistering modifiable %p from notifier %p",
+		m, notifier);
 
 	auto x = registrations.equal_range(m);
 	for ( auto i = x.first; i != x.second; i++ )
 		{
 		if ( i->second == notifier )
 			{
-			registrations.erase(i);
 			--i->first->notifiers;
+			registrations.erase(i);
 			break;
 			}
 		}
@@ -40,9 +40,14 @@ void notifier::Registry::Unregister(Modifiable* m, notifier::Notifier* notifier)
 
 void notifier::Registry::Unregister(Modifiable* m)
 	{
+	DBG_LOG(DBG_NOTIFIERS, "unregistering modifiable %p from all notifiers",
+		m);
+
 	auto x = registrations.equal_range(m);
 	for ( auto i = x.first; i != x.second; i++ )
-		Unregister(m, i->second);
+		--i->first->notifiers;
+
+	registrations.erase(x.first, x.second);
 	}
 
 void notifier::Registry::Modified(Modifiable* m)
@@ -54,8 +59,8 @@ void notifier::Registry::Modified(Modifiable* m)
 		i->second->Modified(m);
 	}
 
-const char* notifier::Notifier::Name() const
+notifier::Modifiable::~Modifiable()
 	{
-	return fmt("%p", this);
+	if ( notifiers )
+		registry.Unregister(this);
 	}
-
diff --git a/src/StateAccess.h b/src/StateAccess.h
index 91a7fa6186..b769e320c0 100644
--- a/src/StateAccess.h
+++ b/src/StateAccess.h
@@ -18,6 +18,7 @@
 #include <string>
 
 #include "util.h"
+#include "DebugLogger.h"
 
 namespace notifier  {
 
@@ -25,11 +26,18 @@ class Modifiable;
 
 class Notifier {
 public:
-	virtual ~Notifier()	{ }
+	Notifier()
+		{
+		DBG_LOG(DBG_NOTIFIERS, "creating notifier %p", this);
+		}
 
-	// Called afger a change has been performed.
+	virtual ~Notifier()
+		{
+		DBG_LOG(DBG_NOTIFIERS, "destroying notifier %p", this);
+		}
+
+	// Called after a change has been performed.
 	virtual void Modified(Modifiable* m) = 0;
-	virtual const char* Name() const;	// for debugging
 };
 
 // Singleton class.
@@ -67,12 +75,7 @@ protected:
 	friend class Registry;
 
 	Modifiable()	{}
-	~Modifiable()
-		{
-		if ( notifiers )
-			registry.Unregister(this);
-
-		};
+	virtual ~Modifiable();
 
 	void Modified()
 		{
diff --git a/src/Stats.cc b/src/Stats.cc
index 1d2a2c8ad8..9489f12f93 100644
--- a/src/Stats.cc
+++ b/src/Stats.cc
@@ -255,7 +255,7 @@ void ProfileLogger::Log()
 		while ( (id = globals->NextEntry(c)) )
 			// We don't show/count internal globals as they are always
 			// contained in some other global user-visible container.
-			if ( id->HasVal() && ! id->IsInternalGlobal() )
+			if ( id->HasVal() )
 				{
 				Val* v = id->ID_Val();
 
diff --git a/src/Trigger.cc b/src/Trigger.cc
index c1295b8218..8de5dff5bd 100644
--- a/src/Trigger.cc
+++ b/src/Trigger.cc
@@ -385,7 +385,7 @@ void Trigger::Register(ID* id)
 	notifier::registry.Register(id, this);
 
 	Ref(id);
-	objs.push_back(id);
+	objs.push_back({id, id});
 	}
 
 void Trigger::Register(Val* val)
@@ -397,13 +397,18 @@ void Trigger::Register(Val* val)
 	notifier::registry.Register(val->Modifiable(), this);
 
 	Ref(val);
-	objs.push_back(val);
+	objs.emplace_back(val, val->Modifiable());
 	}
 
 void Trigger::UnregisterAll()
 	{
+	DBG_LOG(DBG_NOTIFIERS, "%s: unregistering all", Name());
+
 	for ( auto o : objs )
-		Unref(o); // this will unregister with the registry as well
+		{
+		notifier::registry.Unregister(o.second, this);
+		Unref(o.first);
+		}
 
 	objs.clear();
 	}
diff --git a/src/Trigger.h b/src/Trigger.h
index fe7d425a72..3004d30732 100644
--- a/src/Trigger.h
+++ b/src/Trigger.h
@@ -64,7 +64,7 @@ public:
 	void Modified(notifier::Modifiable* m) override
 		{ QueueTrigger(this); }
 
-	const char* Name() const override;
+	const char* Name() const;
 
 	static void QueueTrigger(Trigger* trigger);
 
@@ -102,7 +102,7 @@ private:
 	bool delayed; // true if a function call is currently being delayed
 	bool disabled;
 
-	std::vector<BroObj *> objs;
+	std::vector<std::pair<BroObj *, notifier::Modifiable*>> objs;
 
 	typedef map<const CallExpr*, Val*> ValCache;
 	ValCache cache;
diff --git a/src/Type.h b/src/Type.h
index a97f7360c8..bc8d673443 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -693,10 +693,6 @@ bool is_atomic_type(const BroType* t);
 // True if the given type tag corresponds to a function type.
 #define IsFunc(t)	(t == TYPE_FUNC)
 
-// True if the given type tag corresponds to mutable type.
-#define IsMutable(t)	\
-	(t == TYPE_RECORD || t == TYPE_TABLE || t == TYPE_VECTOR)
-
 // True if the given type type is a vector.
 #define IsVector(t)	(t == TYPE_VECTOR)
 
diff --git a/src/Val.cc b/src/Val.cc
index bea9ce4038..0d6f5838ca 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -349,10 +349,6 @@ void Val::ValDescribeReST(ODesc* d) const
 	}
 	}
 
-MutableVal::~MutableVal()
-	{
-	}
-
 IntervalVal::IntervalVal(double quantity, double units) :
 	Val(quantity * units, TYPE_INTERVAL)
 	{
diff --git a/src/Val.h b/src/Val.h
index d98c352f6d..48bbd50cfc 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -49,7 +49,6 @@ class RecordVal;
 class ListVal;
 class StringVal;
 class EnumVal;
-class MutableVal;
 
 class VectorVal;
 
@@ -320,11 +319,6 @@ public:
 	CONST_CONVERTER(TYPE_STRING, StringVal*, AsStringVal)
 	CONST_CONVERTER(TYPE_VECTOR, VectorVal*, AsVectorVal)
 
-	bool IsMutableVal() const
-		{
-		return IsMutable(type->Tag());
-		}
-
 	void Describe(ODesc* d) const override;
 	virtual void DescribeReST(ODesc* d) const;
 
@@ -486,14 +480,6 @@ private:
 
 extern ValManager* val_mgr;
 
-class MutableVal : public Val {
-protected:
-	explicit MutableVal(BroType* t) : Val(t)	{}
-
-	MutableVal()	{}
-	~MutableVal() override;
-};
-
 #define Microseconds 1e-6
 #define Milliseconds 1e-3
 #define Seconds 1.0
diff --git a/src/bro.bif b/src/bro.bif
index 47b713e4e1..e143cf16e8 100644
--- a/src/bro.bif
+++ b/src/bro.bif
@@ -1819,7 +1819,7 @@ function global_sizes%(%): var_sizes
 
 	ID* id;
 	while ( (id = globals->NextEntry(c)) )
-		if ( id->HasVal() && ! id->IsInternalGlobal() )
+		if ( id->HasVal() )
 			{
 			Val* id_name = new StringVal(id->Name());
 			Val* id_size = val_mgr->GetCount(id->ID_Val()->MemoryAllocation());
@@ -1847,9 +1847,6 @@ function global_ids%(%): id_table
 	ID* id;
 	while ( (id = globals->NextEntry(c)) )
 		{
-		if ( id->IsInternalGlobal() )
-			continue;
-
 		RecordVal* rec = new RecordVal(script_id);
 		rec->Assign(0, new StringVal(type_name(id->Type()->Tag())));
 		rec->Assign(1, val_mgr->GetBool(id->IsExport()));
diff --git a/src/input/readers/config/Config.cc b/src/input/readers/config/Config.cc
index eca276281c..7c1708babd 100644
--- a/src/input/readers/config/Config.cc
+++ b/src/input/readers/config/Config.cc
@@ -33,7 +33,7 @@ Config::Config(ReaderFrontend *frontend) : ReaderBackend(frontend)
 
 	while ( auto id = globals->NextEntry(c) )
 		{
-		if ( id->IsInternalGlobal() || ! id->IsOption() )
+		if ( ! id->IsOption() )
 			continue;
 
 		if ( id->Type()->Tag() == TYPE_RECORD ||