diff --git a/chrome/content/zotero/xpcom/api.js b/chrome/content/zotero/xpcom/api.js
index f3aa9b040..6d69991f9 100644
--- a/chrome/content/zotero/xpcom/api.js
+++ b/chrome/content/zotero/xpcom/api.js
@@ -154,7 +154,7 @@ Zotero.API = {
 			return 'groups/' + Zotero.Groups.getGroupIDFromLibraryID(libraryID);
 		
 		default:
-			throw new Error(`Invalid type '${type}`);
+			throw new Error(`Invalid type '${type}'`);
 		}
 	}
 };