diff --git a/tools/run-mypy b/tools/run-mypy
index c19086fbac..1650a7614b 100755
--- a/tools/run-mypy
+++ b/tools/run-mypy
@@ -13,9 +13,9 @@ os.chdir(ROOT_DIR)
 sys.path.append(ROOT_DIR)
 from tools.lib.test_script import add_provision_check_override_param, assert_provisioning_status_ok
 
-exclude = """
-stubs/
-""".split()
+exclude = [
+    "stubs/",
+]
 
 parser = argparse.ArgumentParser(description="Run mypy on files tracked by git.")
 parser.add_argument("targets", nargs="*", help="files and directories to check (default: .)")