diff --git a/includes/processor_stemmer.inc b/includes/processor_stemmer.inc
index ebb1a9ce..03d9fb03 100644
--- a/includes/processor_stemmer.inc
+++ b/includes/processor_stemmer.inc
@@ -65,7 +65,7 @@ protected function process(&$value) {
         $stemmed[] = $word;
       }
     }
-    $value = implode('', $stemmed);
+    $value = implode(' ', $stemmed);
   }
 
   /**