diff --git a/diff-sha.sh b/diff-sha.sh
index 580f151d2ef..4d6efb73c9a 100644
--- a/diff-sha.sh
+++ b/diff-sha.sh
@@ -245,7 +245,7 @@ else
       depth=$INPUT_FETCH_DEPTH
       max_depth=$INPUT_MAX_FETCH_DEPTH
 
-      for ((i=0; i<max_depth; i*=depth)); do
+      for ((i=0; i<max_depth; i+=depth * 2)); do
         if git diff --name-only --ignore-submodules=all "$PREVIOUS_SHA$DIFF$CURRENT_SHA" 1>/dev/null 2>&1; then
           break
         else