diff --git a/tools/utils.py b/tools/utils.py
index e02cedb..0b5b03e 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -269,7 +269,7 @@
   cmd = ['git', 'rev-parse', 'HEAD']
   PrintCmd(cmd)
   with ChangedWorkingDirectory(checkout):
-    return subprocess.check_output(cmd).strip()
+    return subprocess.check_output(cmd).decode('utf-8').strip()
 
 def makedirs_if_needed(path):
   try: