diff --git a/src/thingdef/thingdef.cpp b/src/thingdef/thingdef.cpp
index 0a02e2763..a1350086b 100644
--- a/src/thingdef/thingdef.cpp
+++ b/src/thingdef/thingdef.cpp
@@ -276,7 +276,7 @@ static void DumpFunction(FILE *dump, VMScriptFunction *sfunc, const char *label,
 static void FinishThingdef()
 {
 	int errorcount = 0;
-	unsigned i, j;
+	unsigned i;
 	int codesize = 0;
 
 #if 1
@@ -289,34 +289,26 @@ static void FinishThingdef()
 		FStateTempCall *tcall = StateTempCalls[i];
 		VMFunction *func;
 
-		assert(tcall->Function != NULL);
-		if (tcall->Parameters.Size() == 0)
+		assert(tcall->Call != NULL);
+		if (tcall->Call->GetArgCount() == 0)
 		{
-			func = tcall->Function;
+			// There are no arguments, so we can call this function directly
+			// without wrapping it in an anonymous function.
+			func = tcall->Call->GetVMFunction();
 		}
 		else
 		{
 			FCompileContext ctx(tcall->ActorClass);
-			for (j = 0; j < tcall->Parameters.Size(); ++j)
-			{
-				tcall->Parameters[j]->Resolve(ctx);
-			}
+			tcall->Call->Resolve(ctx);
 			VMFunctionBuilder buildit;
+
 			// Allocate registers used to pass parameters in.
 			// self, stateowner, state (all are pointers)
 			buildit.Registers[REGT_POINTER].Get(3);
-			// Emit code to pass the standard action function parameters.
-			buildit.Emit(OP_PARAM, 0, REGT_POINTER, 0);
-			buildit.Emit(OP_PARAM, 0, REGT_POINTER, 1);
-			buildit.Emit(OP_PARAM, 0, REGT_POINTER, 2);
-			// Emit code for action parameters.
-			for (j = 0; j < tcall->Parameters.Size(); ++j)
-			{
-				FxExpression *p = /*new FxParameter*/(tcall->Parameters[j]);
-				p->Emit(&buildit);
-				delete p;
-			}
-			buildit.Emit(OP_TAIL_K, buildit.GetConstantAddress(tcall->Function, ATAG_OBJECT), NAP + j, 0);
+
+			// Emit a tail call via FxVMFunctionCall
+			tcall->Call->Emit(&buildit, true);
+
 			VMScriptFunction *sfunc = buildit.MakeFunction();
 			sfunc->NumArgs = NAP;
 			func = sfunc;
@@ -330,6 +322,8 @@ static void FinishThingdef()
 				codesize += sfunc->CodeSize;
 			}
 		}
+		delete tcall->Call;
+		tcall->Call = NULL;
 		for (int k = 0; k < tcall->NumStates; ++k)
 		{
 			tcall->ActorClass->OwnedStates[tcall->FirstState + k].SetAction(func);
diff --git a/src/thingdef/thingdef.h b/src/thingdef/thingdef.h
index 90dd83750..de8d524a1 100644
--- a/src/thingdef/thingdef.h
+++ b/src/thingdef/thingdef.h
@@ -119,11 +119,10 @@ public:
 
 struct FStateTempCall
 {
-	FStateTempCall() : ActorClass(NULL), Function(NULL), FirstState(0), NumStates(0) {}
+	FStateTempCall() : ActorClass(NULL), Call(NULL), FirstState(0), NumStates(0) {}
 
 	PClassActor *ActorClass;
-	VMFunction *Function;
-	TArray<FxExpression *> Parameters;
+	class FxVMFunctionCall *Call;
 	int FirstState;
 	int NumStates;
 };
diff --git a/src/thingdef/thingdef_exp.h b/src/thingdef/thingdef_exp.h
index 8d3c162df..8608557ef 100644
--- a/src/thingdef/thingdef_exp.h
+++ b/src/thingdef/thingdef_exp.h
@@ -798,7 +798,10 @@ public:
 	FxVMFunctionCall(PFunction *func, FArgumentList *args, const FScriptPosition &pos);
 	~FxVMFunctionCall();
 	FxExpression *Resolve(FCompileContext&);
-	ExpEmit Emit(VMFunctionBuilder *build);
+	virtual ExpEmit Emit(VMFunctionBuilder *build);
+	ExpEmit Emit(VMFunctionBuilder *build, bool tailcall);
+	unsigned GetArgCount() { return ArgList == NULL ? 0 : ArgList->Size(); }
+	VMFunction *GetVMFunction() { return Function->Variants[0].Implementation; }
 };
 
 //==========================================================================
diff --git a/src/thingdef/thingdef_expression.cpp b/src/thingdef/thingdef_expression.cpp
index 5fec0cf45..af6f7b52a 100644
--- a/src/thingdef/thingdef_expression.cpp
+++ b/src/thingdef/thingdef_expression.cpp
@@ -3053,17 +3053,23 @@ FxExpression *FxVMFunctionCall::Resolve(FCompileContext& ctx)
 		return NULL;
 	}
 	TArray<PType *> &rets = Function->Variants[0].Proto->ReturnTypes;
-	assert(rets.Size() == 1);
-	ReturnType = rets[0];
-	// If more types are added to ParseNativeVariable(), add them here too.
-		 if (rets[0] == TypeSInt32)		ValueType = VAL_Int;
-	else if (rets[0] == TypeFloat64)	ValueType = VAL_Float;
-	else if (rets[0] == TypeAngle)		ValueType = VAL_Angle;
-	else if (rets[0] == TypeFixed)		ValueType = VAL_Fixed;
+	if (rets.Size() == NULL)
+	{
+		ReturnType = TypeVoid;
+	}
 	else
 	{
-		ValueType = VAL_Int;
-		assert(0 && "Unhandled return type in FxVMFunctionCall::Resolve");
+		ReturnType = rets[0];
+		// If more types are added to ParseNativeVariable(), add them here too.
+			 if (rets[0] == TypeSInt32)		ValueType = VAL_Int;
+		else if (rets[0] == TypeFloat64)	ValueType = VAL_Float;
+		else if (rets[0] == TypeAngle)		ValueType = VAL_Angle;
+		else if (rets[0] == TypeFixed)		ValueType = VAL_Fixed;
+		else
+		{
+			ValueType = VAL_Int;
+			assert(0 && "Unhandled return type in FxVMFunctionCall::Resolve");
+		}
 	}
 	return this;
 }
@@ -3077,6 +3083,11 @@ FxExpression *FxVMFunctionCall::Resolve(FCompileContext& ctx)
 //==========================================================================
 
 ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
+{
+	return Emit(build, false);
+}
+
+ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build, bool tailcall)
 {
 	assert(build->Registers[REGT_POINTER].GetMostUsed() >= 3);
 	int count = ArgList->Size();
@@ -3098,13 +3109,27 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build)
 	{
 		(*ArgList)[i]->Emit(build);
 	}
-	// Get a register to store the return value in
-	assert(ReturnType != NULL);
-	ExpEmit reg(build, ReturnType->GetRegType());
-	// Emit the call itself
-	build->Emit(OP_CALL_K, build->GetConstantAddress(Function->Variants[0].Implementation, ATAG_OBJECT), count, 1);
-	build->Emit(OP_RESULT, 0, reg.RegType, reg.RegNum);
-	return reg;
+	// Get a constant register for this function
+	int funcaddr = build->GetConstantAddress(Function->Variants[0].Implementation, ATAG_OBJECT);
+	// Emit the call
+	if (tailcall)
+	{ // Tail call
+		build->Emit(OP_TAIL_K, funcaddr, count, 0);
+		return ExpEmit();
+	}
+	else if (ReturnType != TypeVoid)
+	{ // Call, expecting one result
+		assert(ReturnType != NULL);
+		ExpEmit reg(build, ReturnType->GetRegType());
+		build->Emit(OP_CALL_K, funcaddr, count, 1);
+		build->Emit(OP_RESULT, 0, reg.RegType, reg.RegNum);
+		return reg;
+	}
+	else
+	{ // Call, expecting no results
+		build->Emit(OP_CALL_K, funcaddr, count, 0);
+		return ExpEmit();
+	}
 }
 
 //==========================================================================
diff --git a/src/thingdef/thingdef_states.cpp b/src/thingdef/thingdef_states.cpp
index 041d3790e..d1c1f8209 100644
--- a/src/thingdef/thingdef_states.cpp
+++ b/src/thingdef/thingdef_states.cpp
@@ -72,24 +72,25 @@ bool DoActionSpecials(FScanner &sc, FState & state, Baggage &bag, FStateTempCall
 	int min_args, max_args;
 	FString specname = sc.String;
 
+	FArgumentList *args = new FArgumentList;
 	int special = P_FindLineSpecial(sc.String, &min_args, &max_args);
 
 	if (special > 0 && min_args >= 0)
 	{
-		tcall->Parameters.Push(new FxParameter(new FxConstant(special, sc)));
+		args->Push(new FxParameter(new FxConstant(special, sc)));
+		i = 0;
 
 		// Make this consistent with all other parameter parsing
 		if (sc.CheckToken('('))
 		{
-			for (i = 0; i < 5;)
+			while (i < 5)
 			{
-				tcall->Parameters.Push(new FxParameter(new FxIntCast(ParseExpression(sc, bag.Info))));
+				args->Push(new FxParameter(new FxIntCast(ParseExpression(sc, bag.Info))));
 				i++;
 				if (!sc.CheckToken (',')) break;
 			}
 			sc.MustGetToken (')');
 		}
-		else i=0;
 
 		if (i < min_args)
 		{
@@ -100,7 +101,7 @@ bool DoActionSpecials(FScanner &sc, FState & state, Baggage &bag, FStateTempCall
 			sc.ScriptError ("Too many arguments to %s", specname.GetChars());
 		}
 
-		tcall->Function = FindGlobalActionFunction("A_CallSpecial")->Variants[0].Implementation;
+		tcall->Call = new FxVMFunctionCall(FindGlobalActionFunction("A_CallSpecial"), args, sc);
 		return true;
 	}
 	return false;
@@ -143,6 +144,7 @@ void ParseStates(FScanner &sc, PClassActor * actor, AActor * defaults, Baggage &
 	FState state;
 	char lastsprite[5] = "";
 	FStateTempCall *tcall = NULL;
+	FArgumentList *args = NULL;
 
 	sc.MustGetStringName ("{");
 	sc.SetEscape(false);	// disable escape sequences in the state parser
@@ -325,8 +327,19 @@ do_stop:
 				PFunction *afd = dyn_cast<PFunction>(bag.Info->Symbols.FindSymbol(FName(sc.String, true), true));
 				if (afd != NULL)
 				{
-					tcall->Function = afd->Variants[0].Implementation;
-					ParseFunctionParameters(sc, bag.Info, tcall->Parameters, afd, statestring, &bag.statedef);
+					// When creating the FxVMFunctionCall, we only pass args if there are any.
+					// So if the previous call had no args, then we can use the argument list
+					// allocated for it. Otherwise, we need to create a new one.
+					if (args == NULL)
+					{
+						args = new FArgumentList;
+					}
+					ParseFunctionParameters(sc, bag.Info, *args, afd, statestring, &bag.statedef);
+					tcall->Call = new FxVMFunctionCall(afd, args->Size() > 0 ? args : NULL, sc);
+					if (args->Size() > 0)
+					{
+						args = NULL;
+					}
 					goto endofstate;
 				}
 				sc.ScriptError("Invalid state parameter %s\n", sc.String);
@@ -339,7 +352,7 @@ endofstate:
 				sc.ScriptError ("Invalid frame character string '%s'", statestring.GetChars());
 				count = -count;
 			}
-			if (tcall->Function != NULL)
+			if (tcall->Call != NULL)
 			{
 				tcall->ActorClass = actor;
 				tcall->FirstState = bag.statedef.GetStateCount() - count;
@@ -353,6 +366,10 @@ endofstate:
 	{
 		delete tcall;
 	}
+	if (args != NULL)
+	{
+		delete args;
+	}
 	sc.SetEscape(true);	// re-enable escape sequences
 }