diff --git a/core/modules/parsers/wikiparser/rules/extlink.js b/core/modules/parsers/wikiparser/rules/extlink.js
index 42c247d22..2a7671c8d 100644
--- a/core/modules/parsers/wikiparser/rules/extlink.js
+++ b/core/modules/parsers/wikiparser/rules/extlink.js
@@ -41,6 +41,7 @@ exports.parse = function() {
 			tag: "a",
 			attributes: {
 				href: {type: "string", value: this.match[0]},
+				"class": {type: "string", value: "tw-tiddlylink-external"},
 				target: {type: "string", value: "_blank"}
 			},
 			children: [{
diff --git a/core/modules/parsers/wikiparser/rules/prettylink.js b/core/modules/parsers/wikiparser/rules/prettylink.js
index 0dffbf0f3..3f1319a22 100644
--- a/core/modules/parsers/wikiparser/rules/prettylink.js
+++ b/core/modules/parsers/wikiparser/rules/prettylink.js
@@ -44,6 +44,7 @@ exports.parse = function() {
 			tag: "a",
 			attributes: {
 				href: {type: "string", value: link},
+				"class": {type: "string", value: "tw-tiddlylink-external"},
 				target: {type: "string", value: "_blank"}
 			},
 			children: [{