diff --git a/chrome/content/zotero/xpcom/integration.js b/chrome/content/zotero/xpcom/integration.js
index a8f89e74dd..cfcd6dba0d 100644
--- a/chrome/content/zotero/xpcom/integration.js
+++ b/chrome/content/zotero/xpcom/integration.js
@@ -1626,7 +1626,7 @@ Zotero.Integration.Fields.prototype.addEditCitation = function(field, callback)
 				try {
 					session.lookupItems(citation);
 				} catch(e) {
-					if(e instanceof MissingItemException) {
+					if(e instanceof Zotero.Integration.MissingItemException) {
 						citation.citationItems = [];
 					} else {
 						throw e;