diff --git a/core/modules/utils/utils.js b/core/modules/utils/utils.js
index 054cfa495..28ada5ace 100644
--- a/core/modules/utils/utils.js
+++ b/core/modules/utils/utils.js
@@ -495,7 +495,7 @@ exports.escapeRegExp = function(s) {
 
 // Checks whether a link target is external, i.e. not a tiddler title
 exports.isLinkExternal = function(to) {
-	var externalRegExp = /(?:file|http|https|mailto|ftp|irc|news|data|skype):[^\s<>{}\[\]`|'"\\^~]+(?:\/|\b)/i;
+	var externalRegExp = /^(?:file|http|https|mailto|ftp|irc|news|data|skype):[^\s<>{}\[\]`|'"\\^~]+(?:\/|\b)$/i;
 	return externalRegExp.test(to);
 };