diff --git a/src/modules/chat/tokenizers.jsx b/src/modules/chat/tokenizers.jsx
index 31084d27..161e17c0 100644
--- a/src/modules/chat/tokenizers.jsx
+++ b/src/modules/chat/tokenizers.jsx
@@ -376,7 +376,7 @@ function mention_processAll(tokens, msg, user, color_mentions) {
 						this.applyHighlight(msg, priority, null, 'mention', true);
 
 					// Push the remaining text from the token.
-					text.push(segment.substr(match[0].length));
+					text.push(segment.slice(match[0].length));
 				}
 
 			} else
diff --git a/src/modules/main_menu/components/chat-tester.vue b/src/modules/main_menu/components/chat-tester.vue
index 521f949b..ef235db5 100644
--- a/src/modules/main_menu/components/chat-tester.vue
+++ b/src/modules/main_menu/components/chat-tester.vue
@@ -438,8 +438,8 @@ export default {
 			if ( idx === -1 )
 				msg.user = null;
 			else {
-				msg.user = msg.prefix.substr(0, idx);
-				msg.prefix = msg.prefix.substr(idx);
+				msg.user = msg.prefix.slice(0, idx);
+				msg.prefix = msg.prefix.slice(idx);
 			}
 
 			return msg;