diff --git a/src/p_teleport.cpp b/src/p_teleport.cpp
index a73ff75e7c..762cd01feb 100644
--- a/src/p_teleport.cpp
+++ b/src/p_teleport.cpp
@@ -79,7 +79,8 @@ void P_SpawnTeleportFog(AActor *mobj, fixed_t x, fixed_t y, fixed_t z, bool befo
 	AActor *mo;
 	if ((beforeTele ? mobj->TeleFogSourceType : mobj->TeleFogDestType) == NULL) //If the actor doesn't have one, initialize the original.
 	{
-		mo = Spawn<ATeleportFog>(x, y, z, ALLOW_REPLACE);
+		//Do nothing.
+		mo = NULL;
 	}
 	else
 	{
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index aa643de8c8..9eda64a81f 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -5395,11 +5395,21 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetTeleFog)
 	ACTION_PARAM_NAME(oldpos, 0);
 	ACTION_PARAM_NAME(newpos, 1);
 	const PClass *check = PClass::FindClass(oldpos);
-	if (check != NULL)
+	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;
 
 	check = PClass::FindClass(newpos);
-	if (check != NULL)
+	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;
 }
 
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index 0c4ec25cbd..b6a2937ae2 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -1422,7 +1422,7 @@ DEFINE_PROPERTY(stamina, I, Actor)
 DEFINE_PROPERTY(telefogsourcetype, S, Actor)
 {
 	PROP_STRING_PARM(str, 0);
-	if (!stricmp(str,"") || *str == 0) defaults->TeleFogSourceType = PClass::FindClass("TeleportFog");
+	if (!stricmp(str, "") || (!stricmp(str, "none")) || (!stricmp(str, "null")) || *str == 0) defaults->TeleFogSourceType = NULL;
 	else defaults->TeleFogSourceType = FindClassTentative(str,"TeleportFog");
 }
 
@@ -1432,7 +1432,7 @@ DEFINE_PROPERTY(telefogsourcetype, S, Actor)
 DEFINE_PROPERTY(telefogdesttype, S, Actor)
 {
 	PROP_STRING_PARM(str, 0);
-	if (!stricmp(str, "") || *str == 0) defaults->TeleFogDestType = PClass::FindClass("TeleportFog");
+	if (!stricmp(str, "") || (!stricmp(str, "none")) || (!stricmp(str, "null")) || *str == 0) defaults->TeleFogDestType = NULL;
 	else defaults->TeleFogDestType = FindClassTentative(str, "TeleportFog");
 }