diff --git a/chrome/content/zotero/xpcom/sync.js b/chrome/content/zotero/xpcom/sync.js
index 3c2eae218c..aed5821741 100644
--- a/chrome/content/zotero/xpcom/sync.js
+++ b/chrome/content/zotero/xpcom/sync.js
@@ -884,7 +884,7 @@ Zotero.Sync.Runner = new function () {
 						);
 						
 						if (index == 1) {
-							setTimeout(buttonCallback, 1);
+							setTimeout(function () { buttonCallback(); }, 1);
 						}
 					}
 					
@@ -920,7 +920,7 @@ Zotero.Sync.Runner = new function () {
 						);
 						
 						if (index == 1) {
-							setTimeout(function () { buttonCallback }, 1);
+							setTimeout(function () { buttonCallback(); }, 1);
 						}
 					}
 				}