diff --git a/app/assets/javascripts/discourse/dialects/bbcode_dialect.js b/app/assets/javascripts/discourse/dialects/bbcode_dialect.js
index 5942857ede8..ba6f4b5b303 100644
--- a/app/assets/javascripts/discourse/dialects/bbcode_dialect.js
+++ b/app/assets/javascripts/discourse/dialects/bbcode_dialect.js
@@ -90,7 +90,7 @@ replaceBBCodeParamsRaw("email", function(param, contents) {
 });
 
 replaceBBCodeParams("size", function(param, contents) {
-  return ['span', {'class': "bbcode-size-" + (parseInt(param) || 1)}].concat(contents);
+  return ['span', {'class': "bbcode-size-" + (parseInt(param, 10) || 1)}].concat(contents);
 });
 
 // Handles `[code] ... [/code]` blocks