--- a/hedgewars/uLandObjects.pas	Mon Aug 19 18:59:24 2019 +0300
+++ b/hedgewars/uLandObjects.pas	Mon Aug 19 21:17:18 2019 +0300
@@ -959,7 +959,8 @@
             Delete(s, 1, i);
             if (Maxcnt < 1) or (Maxcnt > MAXTHEMEOBJECTS) then
                 OutError('Broken theme. Object''s max. count should be between 1 and '+ inttostr(MAXTHEMEOBJECTS) +' (it was '+ inttostr(Maxcnt) +').', true);
-            ChecksumLandObjectImage(Surf, true);
+            if Mask = nil then
+                ChecksumLandObjectImage(Surf, true);
             ChecksumLandObjectImage(Mask, false);
 
             inrectcnt := 0;