diff --git a/FU.pm b/FU.pm
index 1f71a91..04809b5 100644
--- a/FU.pm
+++ b/FU.pm
@@ -216,7 +216,7 @@ sub _monitor {
                 die if $m > $data{$_};
             },
             no_chdir => 1
-        }, $scriptpath, values %INC, @monitor_paths);
+        }, grep -e, $scriptpath, values %INC, @monitor_paths);
         0
     } // 1;
 }