diff --git a/module/VuFind/src/VuFind/RecordDriver/WorldCat.php b/module/VuFind/src/VuFind/RecordDriver/WorldCat.php
index bfe57c6d7fe756e92c924786fdb04743c4eb3f24..7fcefa1d3cd8b0bc39fdbcbc73f651bcd257b681 100644
--- a/module/VuFind/src/VuFind/RecordDriver/WorldCat.php
+++ b/module/VuFind/src/VuFind/RecordDriver/WorldCat.php
@@ -165,7 +165,8 @@ class WorldCat extends SolrMarc
                 $retVal[] = $callNo;
             }
         }
-        if (!empty($dewey = $this->getDeweyCallNumber())) {
+        $dewey = $this->getDeweyCallNumber();
+        if (!empty($dewey)) {
             $retVal[] = $dewey;
         }
         return $retVal;