diff --git a/polymer/eduke32/build/src/polymer.c b/polymer/eduke32/build/src/polymer.c
index c3799ade6..9c3f87984 100644
--- a/polymer/eduke32/build/src/polymer.c
+++ b/polymer/eduke32/build/src/polymer.c
@@ -2387,6 +2387,8 @@ static int32_t      polymer_updatesector(int16_t sectnum)
         s->floorheinum = sec->floorheinum;
         s->ceilingheinum = sec->ceilingheinum;
     }
+    else if (sec->visibility != s->visibility)
+        wallinvalidate = 1;
 
     floorpicnum = sec->floorpicnum;
     DO_TILE_ANIM(floorpicnum, sectnum);