diff --git a/lib/irc.js b/lib/irc.js
index 2dfe737..16dfd6c 100644
--- a/lib/irc.js
+++ b/lib/irc.js
@@ -298,7 +298,7 @@ export function isHighlight(msg, nick, cm) {
 		if (i > 0) {
 			left = text[i - 1];
 		}
-		if (i < text.length) {
+		if (i + nick.length < text.length) {
 			right = text[i + nick.length];
 		}
 		if (isWordBoundary(left) && isWordBoundary(right)) {