diff --git a/git_map_branches.py b/git_map_branches.py
index 8b792f34c..c310dde73 100755
--- a/git_map_branches.py
+++ b/git_map_branches.py
@@ -33,6 +33,7 @@ from git_common import current_branch, upstream, tags, get_branches_info
 from git_common import get_git_version, MIN_UPSTREAM_TRACK_GIT_VERSION, hash_one
 from git_common import get_config, run
 
+import gclient_utils
 import setup_color
 
 from third_party.colorama import Fore, Style
@@ -339,6 +340,10 @@ def print_desc():
 
 @metrics.collector.collect_metrics('git map-branches')
 def main(argv):
+    if gclient_utils.IsEnvCog():
+        print('map-branches command is not supported in non-git environment.',
+              file=sys.stderr)
+        return 1
     setup_color.init()
     if get_git_version() < MIN_UPSTREAM_TRACK_GIT_VERSION:
         print(