struct tree_desc desc;
        unsigned o_mode;
        const char *o_name;
-       const unsigned char *o_sha1;
 
        init_tree_desc(&desc, item->buffer, item->size);
 
        o_mode = 0;
        o_name = NULL;
-       o_sha1 = NULL;
 
        while (desc.size) {
                unsigned mode;
                const char *name;
-               const unsigned char *sha1;
 
-               sha1 = tree_entry_extract(&desc, &name, &mode);
+               tree_entry_extract(&desc, &name, &mode);
 
                if (strchr(name, '/'))
                        has_full_path = 1;
 
                o_mode = mode;
                o_name = name;
-               o_sha1 = sha1;
        }
 
        retval = 0;
        struct commit_graft *graft;
        int parents = 0;
 
-       if (!commit->date)
+       if (commit->date == ULONG_MAX)
                return error_func(&commit->object, FSCK_ERROR, "invalid author/committer line");
 
        if (memcmp(buffer, "tree ", 5))