diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 55958d3..4db937e 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -19,7 +19,7 @@
 def _DoClangFormat(input_api, output_api):
     if platform.system() == 'Linux' and platform.architecture()[0] == '64bit':
         clang_format_path = 'buildtools/linux64/clang-format'
-    elif platform.system() == 'Mac':
+    elif platform.system() == 'Darwin':
         clang_format_path = 'buildtools/mac/clang-format'
     elif platform.system() == 'Windows':
         clang_format_path = 'buildtools/win/clang-format.exe'