diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index d5b871b21d..564cfcac4f 100644
--- a/builtin/get-tar-commit-id.c
+++ b/builtin/get-tar-commit-id.c
@@ -35,7 +35,7 @@ int cmd_get_tar_commit_id(int argc, const char **argv UNUSED, const char *prefix
 		die_errno("git get-tar-commit-id: read error");
 	if (n != HEADERSIZE)
 		die_errno("git get-tar-commit-id: EOF before reading tar header");
-	if (header->typeflag[0] != 'g')
+	if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
 		return 1;
 
 	len = strtol(content, &end, 10);