diff --git a/diff-sha.sh b/diff-sha.sh
index 752705a2..8d9ac33d 100644
--- a/diff-sha.sh
+++ b/diff-sha.sh
@@ -248,15 +248,17 @@ else
       for ((i=0; i<max_depth; i+=depth)); do
         if git diff --name-only --ignore-submodules=all "$PREVIOUS_SHA$DIFF$CURRENT_SHA" 1>/dev/null 2>&1; then
           break
+        else
+          PREVIOUS_SHA=$(git merge-base --fork-point "$PREVIOUS_SHA" "$CURRENT_SHA" 2>&1) && exit_status=$? || exit_status=$?
         fi
-        
+
         echo "Fetching $i commits..."
 
         # shellcheck disable=SC2086
         git fetch $EXTRA_ARGS -u --progress --deepen="$i" origin $TARGET_BRANCH $CURRENT_SHA 1>/dev/null 2>&1
       done
 
-      if ((i > max_depth)); then
+      if ((i >= max_depth)); then
         echo "::error::Unable to locate a common ancestor between $TARGET_BRANCH and $CURRENT_BRANCH with: $PREVIOUS_SHA$DIFF$CURRENT_SHA"
         exit 1
       fi