diff --git a/fp-plugins/prettyurls/plugin.prettyurls.php b/fp-plugins/prettyurls/plugin.prettyurls.php
index 7731c91..5c4a8c3 100644
--- a/fp-plugins/prettyurls/plugin.prettyurls.php
+++ b/fp-plugins/prettyurls/plugin.prettyurls.php
@@ -169,6 +169,7 @@ class Plugin_PrettyURLs {
 		if (PRETTYURLS_TITLES) {	
 			if ($c = array_search($matches[1], $this->categories))
 				$this->fp_params['cat'] = $c;
+			else return $matches[0];
 		} else {
 			$this->fp_params['cat'] = $matches[1];
 		}