diff --git a/src/p_pspr.h b/src/p_pspr.h
index 9bb8366bb..9d3b78ea4 100644
--- a/src/p_pspr.h
+++ b/src/p_pspr.h
@@ -59,6 +59,8 @@ extern "C" {
 #define FF_REVERSESUBTRACT	((AST_REVERSESUBTRACT-1)<<FF_BLENDSHIFT)
 #define FF_MODULATE			((AST_MODULATE-1)<<FF_BLENDSHIFT)
 #define FF_OVERLAY			((AST_OVERLAY-1)<<FF_BLENDSHIFT)
+/// \brief Frame flags: B/W inverted colors (hitlag flashing)
+#define FF_INVERT 0x8000
 
 /// \brief Frame flags: 0 = no trans(opaque), 1-15 = transl. table
 #define FF_TRANSMASK 0xf0000
diff --git a/src/r_things.c b/src/r_things.c
index a890676ca..ca164a398 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -815,6 +815,7 @@ static boolean baddie_is_flashing(mobj_t *thing)
 boolean R_ThingIsFlashing(mobj_t *thing)
 {
 	return
+		(thing->frame & FF_INVERT) ||
 		hitlag_is_flashing(thing) ||
 		baddie_is_flashing(thing);
 }