diff --git a/polymer/eduke32/build/include/editor.h b/polymer/eduke32/build/include/editor.h
index 1afb63c62..a345c62c0 100644
--- a/polymer/eduke32/build/include/editor.h
+++ b/polymer/eduke32/build/include/editor.h
@@ -121,7 +121,7 @@ extern void M32_ResetFakeRORTiles(void);
 extern int32_t kopen4loadfrommod(const char *filename, char searchfirst);
 
 // set to 1 to enable:
-#define M32_UNDO 0
+#define M32_UNDO 1
 extern int32_t map_revision;
 extern int32_t map_undoredo(int32_t dir);
 extern void map_undoredo_free(void);
diff --git a/polymer/eduke32/source/astub.c b/polymer/eduke32/source/astub.c
index f199f6faf..b43066ff6 100644
--- a/polymer/eduke32/source/astub.c
+++ b/polymer/eduke32/source/astub.c
@@ -622,8 +622,6 @@ int32_t map_undoredo(int32_t dir)
         insertsprite(sprite[i].sectnum,sprite[i].statnum);
     }
 
-    // XXX: this fails currently! the decompressed sprites have
-    //  .statnum==MAXSTATUS and .sectnum==MAXSECTORS.  WTF?!
     assert(Numsprites == mapstate->numsprites);
 
 #ifdef POLYMER