diff --git a/src/dehacked.c b/src/dehacked.c
index 0dbfe3318..4c36639a2 100644
--- a/src/dehacked.c
+++ b/src/dehacked.c
@@ -8847,7 +8847,7 @@ static const char *const MOBJEFLAG_LIST[] = {
 
 #ifdef HAVE_BLUA
 static const char *const MAPTHINGFLAG_LIST[4] = {
-	NULL,
+	"EXTRA", // Extra flag for objects.
 	"OBJECTFLIP", // Reverse gravity flag for objects.
 	"OBJECTSPECIAL", // Special flag used with certain objects.
 	"AMBUSH" // Deaf monsters/do not react to sound.