names[i] = argv[i];
                if (read_mmfile(mmfs + i, fname))
                        return -1;
-               if (buffer_is_binary(mmfs[i].ptr, mmfs[i].size))
+               if (mmfs[i].size > MAX_XDIFF_SIZE ||
+                   buffer_is_binary(mmfs[i].ptr, mmfs[i].size))
                        return error("Cannot merge binary files: %s",
                                        argv[i]);
        }
                free(result.ptr);
        }
 
+       if (ret > 127)
+               ret = 127;
+
        return ret;
 }