diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index ccf5aa4293..b3370cd862 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -107,6 +107,7 @@
 		<li>[Fix] Check error reporting level for all error level. This fixes a problem for hosts having manipulated the error handler. (Bug #14831)</li>
 		<li>[Fix] Recache Moderators when copying permissions. (Bug #15384)</li>
 		<li>[Fix] Propagate sort options in mcp_forums (Bug #15464)</li>
+		<li>[Change] Do not allow [size=0] bbcodes (font-size of 0)</li>
 
 	</ul>
 
diff --git a/phpBB/includes/message_parser.php b/phpBB/includes/message_parser.php
index acc4547039..6e601e1499 100644
--- a/phpBB/includes/message_parser.php
+++ b/phpBB/includes/message_parser.php
@@ -208,6 +208,12 @@ class bbcode_firstpass extends bbcode
 			return '[size=' . $stx . ']' . $in . '[/size]';
 		}
 
+		// Do not allow size=0
+		if ($stx <= 0)
+		{
+			return '[size=' . $stx . ']' . $in . '[/size]';
+		}
+
 		return '[size=' . $stx . ':' . $this->bbcode_uid . ']' . $in . '[/size:' . $this->bbcode_uid . ']';
 	}