diff --git a/FTagDumper/grid/grid-submit b/FTagDumper/grid/grid-submit
index 6d07e4b732d97643f679658159c1d011fe41c3b5..abb9576953907daa8f9663e198e5556d1a0aa969 100755
--- a/FTagDumper/grid/grid-submit
+++ b/FTagDumper/grid/grid-submit
@@ -226,6 +226,9 @@ fi
 
 # check for uncontrolled changes
 if [[ ! $FORCE ]]; then
+    # without refreshing first, diff-index might report changes, even
+    # though it's only timestamps and not actual file content
+    git -C ${BASE} update-index --refresh
     if ! git -C ${BASE} diff-index --quiet HEAD; then
         echo "ERROR: uncommitted changes, please commit them" >&2; exit 1
     fi