diff --git a/script/run-clang-format.py b/script/run-clang-format.py
index dcec3de7a8..2cb17a5908 100644
--- a/script/run-clang-format.py
+++ b/script/run-clang-format.py
@@ -325,6 +325,7 @@ def main():
                 retcode = ExitStatus.DIFF
 
     if patch_file.tell() == 0:
+      patch_file.close()
       os.unlink(patch_file.name)
     else:
       print("\nTo patch these files, run:\n$ git apply {}\n"