diff --git a/pre_commit/staged_files_only.py b/pre_commit/staged_files_only.py
index c8ee9c29..7719d28b 100644
--- a/pre_commit/staged_files_only.py
+++ b/pre_commit/staged_files_only.py
@@ -23,7 +23,7 @@ def staged_files_only(cmd_runner):
     retcode, diff_stdout_binary, _ = cmd_runner.run(
         [
             'git', 'diff', '--ignore-submodules', '--binary', '--exit-code',
-            '--no-color',
+            '--no-color', '--no-ext-diff',
         ],
         retcode=None,
         encoding=None,