diff --git a/core/modules/parsers/wikiparser/rules/commentblock.js b/core/modules/parsers/wikiparser/rules/commentblock.js
index 84ee897ba..b7651c272 100644
--- a/core/modules/parsers/wikiparser/rules/commentblock.js
+++ b/core/modules/parsers/wikiparser/rules/commentblock.js
@@ -31,7 +31,7 @@ exports.findNextMatch = function(startPos) {
 	this.matchRegExp.lastIndex = startPos;
 	this.match = this.matchRegExp.exec(this.parser.source);
 	if(this.match) {
-		this.endMatchRegExp.lastIndex = startPos + this.match[0].length;
+		this.endMatchRegExp.lastIndex = this.match.index + this.match[0].length;
 		this.endMatch = this.endMatchRegExp.exec(this.parser.source);
 		if(this.endMatch) {
 			return this.match.index;
diff --git a/core/modules/parsers/wikiparser/rules/commentinline.js b/core/modules/parsers/wikiparser/rules/commentinline.js
index 6e697e6c0..671bd79d6 100644
--- a/core/modules/parsers/wikiparser/rules/commentinline.js
+++ b/core/modules/parsers/wikiparser/rules/commentinline.js
@@ -31,7 +31,7 @@ exports.findNextMatch = function(startPos) {
 	this.matchRegExp.lastIndex = startPos;
 	this.match = this.matchRegExp.exec(this.parser.source);
 	if(this.match) {
-		this.endMatchRegExp.lastIndex = startPos + this.match[0].length;
+		this.endMatchRegExp.lastIndex = this.match.index + this.match[0].length;
 		this.endMatch = this.endMatchRegExp.exec(this.parser.source);
 		if(this.endMatch) {
 			return this.match.index;