diff --git a/core/modules/editor/operations/text/prefix-lines.js b/core/modules/editor/operations/text/prefix-lines.js
index 6d065298b..d511b4b06 100644
--- a/core/modules/editor/operations/text/prefix-lines.js
+++ b/core/modules/editor/operations/text/prefix-lines.js
@@ -21,7 +21,7 @@ exports["prefix-lines"] = function(event,operation) {
 	var lines = operation.text.substring(operation.cutStart,operation.cutEnd).split(/\r?\n/mg);
 	$tw.utils.each(lines,function(line,index) {
 		// Compose the required prefix
-		var prefix = event.paramObject.character.repeat(event.paramObject.count);
+		var prefix = $tw.utils.repeat(event.paramObject.character,event.paramObject.count);
 		// Check if we already have the required prefix
 		if(line.substring(0,prefix.length) === prefix) {
 			// If so, remove the prefix
diff --git a/core/modules/utils/utils.js b/core/modules/utils/utils.js
index 2bea63728..054cfa495 100644
--- a/core/modules/utils/utils.js
+++ b/core/modules/utils/utils.js
@@ -17,7 +17,18 @@ Display a warning, in colour if we're on a terminal
 */
 exports.warning = function(text) {
 	console.log($tw.node ? "\x1b[1;33m" + text + "\x1b[0m" : text);
-}
+};
+
+/*
+Repeats a string
+*/
+exports.repeat = function(str,count) {
+	var result = "";
+	for(var t=0;t<count;t++) {
+		result += str;
+	}
+	return result;
+};
 
 /*
 Trim whitespace from the start and end of a string