diff --git a/src/p_map.c b/src/p_map.c
index d96afc08d..b72ce2145 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -745,6 +745,10 @@ static BlockItReturn_t PIT_CheckThing(mobj_t *thing)
 
 	if (tm.thing->type == MT_INSTAWHIP)
 	{
+		if (tm.thing->z > thing->z + thing->height)
+			return BMIT_CONTINUE; // overhead
+		if (tm.thing->z + tm.thing->height < thing->z)
+			return BMIT_CONTINUE; // underneath
 		K_InstaWhipCollide(tm.thing, thing);
 		return BMIT_CONTINUE;
 	}