diff --git a/polymer/eduke32/build/src/build.c b/polymer/eduke32/build/src/build.c
index 6b12c3c25..23332dd8f 100644
--- a/polymer/eduke32/build/src/build.c
+++ b/polymer/eduke32/build/src/build.c
@@ -1621,7 +1621,10 @@ void ovh_whiteoutgrab(int32_t restoreredwalls)
             wall[j].nextsector = -1;
         }
 
-    mkonwvalid();
+    if (highlightsectorcnt > 0)
+        mkonwvalid();
+    else
+        mkonwinvalid();
 }
 
 static void duplicate_selected_sectors(void)
@@ -6896,6 +6899,7 @@ CANCEL:
             checksectorpointer(j, highlightsector[i]);
         }
     }
+    mkonwinvalid();
 
     fixspritesectors();
 
diff --git a/polymer/eduke32/source/astub.c b/polymer/eduke32/source/astub.c
index 57e2046bb..e7312a202 100644
--- a/polymer/eduke32/source/astub.c
+++ b/polymer/eduke32/source/astub.c
@@ -11290,6 +11290,8 @@ void ExtCheckKeys(void)
         {
 #if M32_UNDO
             create_map_snapshot();
+#else
+            CheckMapCorruption(6, 0);
 #endif
             asksave++;
         }