diff --git a/pre_commit/git.py b/pre_commit/git.py
index 67499cdb8..853f4b0d0 100644
--- a/pre_commit/git.py
+++ b/pre_commit/git.py
@@ -43,6 +43,7 @@ def no_git_env(
         k in {
             'GIT_EXEC_PATH', 'GIT_SSH', 'GIT_SSH_COMMAND', 'GIT_SSL_CAINFO',
             'GIT_SSL_NO_VERIFY', 'GIT_CONFIG_COUNT',
+            'GIT_HTTP_PROXY_AUTHMETHOD',
         }
     }