diff --git a/diff-sha.sh b/diff-sha.sh
index 25c715d0..626a5cf2 100644
--- a/diff-sha.sh
+++ b/diff-sha.sh
@@ -157,7 +157,7 @@ else
   fi
 fi
 
-if [[ -n "$PREVIOUS_SHA" && -n "$CURRENT_SHA" && "$PREVIOUS_SHA" == "$CURRENT_SHA" && "$INITIAL_COMMIT" == "false" ]]; then
+if [[ "$PREVIOUS_SHA" == "$CURRENT_SHA" && "$INITIAL_COMMIT" == "false" ]]; then
   echo "::error::Similar commit hashes detected: previous sha: $PREVIOUS_SHA is equivalent to the current sha: $CURRENT_SHA"
   echo "::error::You seem to be missing 'fetch-depth: 0' or 'fetch-depth: 2'. See https://github.com/tj-actions/changed-files#usage"
   exit 1