o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
        else if (!strcmp(s, "histogram"))
                o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
+       else if (!strcmp(s, "diff-algorithm=")) {
+               long value = parse_algorithm_value(s+15);
+               if (value < 0)
+                       return -1;
+               /* clear out previous settings */
+               DIFF_XDL_CLR(o, NEED_MINIMAL);
+               o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
+               o->xdl_opts |= value;
+       }
        else if (!strcmp(s, "ignore-space-change"))
                o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
        else if (!strcmp(s, "ignore-all-space"))