diff --git a/public/src/client/category/tools.js b/public/src/client/category/tools.js
index 4c214d5067..b941e398bc 100644
--- a/public/src/client/category/tools.js
+++ b/public/src/client/category/tools.js
@@ -119,6 +119,9 @@ define('forum/category/tools', [
 
 		components.get('topic/tag').on('click', async function () {
 			const tids = topicSelect.getSelectedTids();
+			if (!tids.length) {
+				return alerts.error('[[error:no-topics-selected]]');
+			}
 			const topics = await Promise.all(tids.map(tid => api.get(`/topics/${tid}`)));
 			require(['forum/topic/tag'], function (tag) {
 				tag.init(topics, ajaxify.data.tagWhitelist, onCommandComplete);