diff --git a/src/undo.c b/src/undo.c
index 034d16c..c29832b 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -1614,8 +1614,8 @@
 #endif
     }
 
-    /* strip any s-bit */
-    perm = perm & 0777;
+    /* strip any s-bit and executable bit */
+    perm = perm & 0666;
 
     /* If the undo file already exists, verify that it actually is an undo
      * file, and delete it. */