static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 static const char *default_ll_merge;
 
-static int read_merge_config(const char *var, const char *value)
+static int read_merge_config(const char *var, const char *value, void *cb)
 {
        struct ll_merge_driver *fn;
        const char *ep, *name;
        if (ll_user_merge_tail)
                return;
        ll_user_merge_tail = &ll_user_merge;
-       git_config(read_merge_config);
+       git_config(read_merge_config, NULL);
 }
 
 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)