diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 03f011b41..309392191 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -4604,7 +4604,7 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetSpecial)
 //
 //===========================================================================
 
-static PField *GetVar(AActor *self, FName varname)
+static PField *GetVar(DObject *self, FName varname)
 {
 	PField *var = dyn_cast<PField>(self->GetClass()->Symbols.FindSymbol(varname, true));
 
@@ -4619,7 +4619,8 @@ static PField *GetVar(AActor *self, FName varname)
 
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserVar)
 {
-	PARAM_ACTION_PROLOGUE;
+	PARAM_PROLOGUE;
+	PARAM_OBJECT(self, DObject);
 	PARAM_NAME	(varname);
 	PARAM_INT	(value);
 
@@ -4634,7 +4635,8 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserVar)
 
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserVarFloat)
 {
-	PARAM_ACTION_PROLOGUE;
+	PARAM_PROLOGUE;
+	PARAM_OBJECT(self, DObject);
 	PARAM_NAME	(varname);
 	PARAM_FLOAT	(value);
 
@@ -4653,7 +4655,7 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserVarFloat)
 //
 //===========================================================================
 
-static PField *GetArrayVar(AActor *self, FName varname, int pos)
+static PField *GetArrayVar(DObject *self, FName varname, int pos)
 {
 	PField *var = dyn_cast<PField>(self->GetClass()->Symbols.FindSymbol(varname, true));
 
@@ -4676,7 +4678,8 @@ static PField *GetArrayVar(AActor *self, FName varname, int pos)
 
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserArray)
 {
-	PARAM_ACTION_PROLOGUE;
+	PARAM_PROLOGUE;
+	PARAM_OBJECT(self, DObject);
 	PARAM_NAME	(varname);
 	PARAM_INT	(pos);
 	PARAM_INT	(value);
@@ -4693,7 +4696,8 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserArray)
 
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetUserArrayFloat)
 {
-	PARAM_ACTION_PROLOGUE;
+	PARAM_PROLOGUE;
+	PARAM_OBJECT(self, DObject);
 	PARAM_NAME	(varname);
 	PARAM_INT	(pos);
 	PARAM_FLOAT	(value);
diff --git a/src/thingdef/thingdef_parse.cpp b/src/thingdef/thingdef_parse.cpp
index a86be2bc9..e4488de45 100644
--- a/src/thingdef/thingdef_parse.cpp
+++ b/src/thingdef/thingdef_parse.cpp
@@ -473,7 +473,7 @@ static void ParseNativeFunction(FScanner &sc, PClassActor *cls)
 		FScriptPosition::ErrorCounter++;
 	}
 
-	// Read the type and make sure it's int or float.
+	// Read the type and make sure it's acceptable.
 	sc.MustGetAnyToken();
 	switch (sc.TokenType)
 	{
@@ -490,6 +490,9 @@ static void ParseNativeFunction(FScanner &sc, PClassActor *cls)
 		rets.Push(TypeState);
 		break;
 
+	case TK_Void:
+		break;
+
 	case TK_Identifier:
 		rets.Push(NewPointer(RUNTIME_CLASS(DObject)));
 		// Todo: Object type
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index 2aecefafa..d02c7d1d7 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -274,10 +274,10 @@ ACTOR Actor native //: Thinker
 	action native A_ScaleVelocity(float scale, int ptr = AAPTR_DEFAULT);
 	action native A_ChangeVelocity(float x = 0, float y = 0, float z = 0, int flags = 0, int ptr = AAPTR_DEFAULT);
 	action native A_SetArg(int pos, int value);
-	action native A_SetUserVar(name varname, int value);
-	action native A_SetUserArray(name varname, int index, int value);
-	action native A_SetUserVarFloat(name varname, float value);
-	action native A_SetUserArrayFloat(name varname, int index, float value);
+	native void A_SetUserVar(name varname, int value);
+	native void A_SetUserArray(name varname, int index, int value);
+	native void A_SetUserVarFloat(name varname, float value);
+	native void A_SetUserArrayFloat(name varname, int index, float value);
 	action native A_SetSpecial(int spec, int arg0 = 0, int arg1 = 0, int arg2 = 0, int arg3 = 0, int arg4 = 0);
 	action native A_Quake(int intensity, int duration, int damrad, int tremrad, sound sfx = "world/quake");
 	action native A_QuakeEx(int intensityX, int intensityY, int intensityZ, int duration, int damrad, int tremrad, sound sfx = "world/quake", int flags = 0, float mulWaveX = 1, float mulWaveY = 1, float mulWaveZ = 1, int falloff = 0, int highpoint = 0);