diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index 427e64008..e9153a071 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, "TeleportFog")) defaults->TeleFogSourceType = NAME_None;
+	if (str == NULL) defaults->TeleFogSourceType = "TeleportFog";
 	else defaults->TeleFogSourceType = str;
 }
 
@@ -1432,8 +1432,8 @@ DEFINE_PROPERTY(telefogsourcetype, S, Actor)
 DEFINE_PROPERTY(telefogdesttype, S, Actor)
 {
 	PROP_STRING_PARM(str, 0);
-	if (!stricmp(str, "TeleportFog")) defaults->TeleFogDestType = NAME_None;
-	else defaults->TeleFogDestType = str;
+	if (str == NULL) defaults->TeleFogSourceType = "TeleportFog";
+	defaults->TeleFogDestType = str;
 }
 
 //==========================================================================