static const char *better_branch_name(const char *branch)
 {
-       static char githead_env[8 + GIT_SHA1_HEXSZ + 1];
+       static char githead_env[8 + GIT_MAX_HEXSZ + 1];
        char *name;
 
-       if (strlen(branch) != GIT_SHA1_HEXSZ)
+       if (strlen(branch) != the_hash_algo->hexsz)
                return branch;
        xsnprintf(githead_env, sizeof(githead_env), "GITHEAD_%s", branch);
        name = getenv(githead_env);