diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index f6e3425bc..cb59f8a1f 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -5726,33 +5726,17 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_Remove)
 // A_SetTeleFog
 //
 // Sets the teleport fog(s) for the calling actor.
-// Takes a name of the classes for te source and destination. 
-// Can set both at the same time. Use "" to retain the previous fog without
-// changing it.
+// Takes a name of the classes for the source and destination.
 //===========================================================================
 
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetTeleFog)
 {
 	ACTION_PARAM_START(2);
-	ACTION_PARAM_NAME(oldpos, 0);
-	ACTION_PARAM_NAME(newpos, 1);
-	const PClass *check = PClass::FindClass(oldpos);
-	if (check == NULL || !stricmp(oldpos, "none") || !stricmp(oldpos, "null"))
-		self->TeleFogSourceType = NULL;
-	else if (!stricmp(oldpos, ""))
-	{ //Don't change it if it's just ""
-	}
-	else
-		self->TeleFogSourceType = check;
+	ACTION_PARAM_CLASS(oldpos, 0);
+	ACTION_PARAM_CLASS(newpos, 1);
 
-	check = PClass::FindClass(newpos);
-	if (check == NULL || !stricmp(newpos, "none") || !stricmp(newpos, "null"))
-		self->TeleFogDestType = NULL;
-	else if (!stricmp(newpos, ""))
-	{ //Don't change it if it's just ""
-	}
-	else
-		self->TeleFogDestType = check;
+	self->TeleFogSourceType = oldpos;
+	self->TeleFogDestType = newpos;
 }
 
 //===========================================================================
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index f84151d18..d85717ead 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -325,7 +325,7 @@ ACTOR Actor native //: Thinker
 	action native A_GiveToSiblings(class<Inventory> itemtype, int amount = 0);
 	action native A_TakeFromChildren(class<Inventory> itemtype, int amount = 0);
 	action native A_TakeFromSiblings(class<Inventory> itemtype, int amount = 0);
-	action native A_SetTeleFog(name oldpos, name newpos);
+	action native A_SetTeleFog(class<TeleportFog> oldpos, class<TeleportFog> newpos);
 	action native A_SwapTeleFog();
 	action native A_SetFloatBobPhase(int bob);
 	action native A_SetHealth(int health, int ptr = AAPTR_DEFAULT);