diff --git a/phpBB/includes/acp/acp_bbcodes.php b/phpBB/includes/acp/acp_bbcodes.php
index 82c6ed778b..236043f339 100644
--- a/phpBB/includes/acp/acp_bbcodes.php
+++ b/phpBB/includes/acp/acp_bbcodes.php
@@ -133,6 +133,11 @@ class acp_bbcodes
 					}
 				}
 
+				if (strlen($data['first_pass_match']) >= 255 || strlen($data['first_pass_replace']) >= 255 || strlen($data['second_pass_match']) >= 255)
+				{
+					trigger_error('BBCODE_TAG_TOO_LONG');
+				}
+
 				$sql_ary = array(
 					'bbcode_tag'				=> $data['bbcode_tag'],
 					'bbcode_match'				=> $bbcode_match,
diff --git a/phpBB/language/en/acp/posting.php b/phpBB/language/en/acp/posting.php
index 0b769c7743..e1941b7f8d 100644
--- a/phpBB/language/en/acp/posting.php
+++ b/phpBB/language/en/acp/posting.php
@@ -42,6 +42,7 @@ $lang = array_merge($lang, array(
 	'BBCODE_HELPLINE_EXPLAIN'	=> 'This field contains the mouseover text of the BBCode',
 	'BBCODE_HELPLINE_TEXT'		=> 'Helpline text',
 	'BBCODE_TAG'				=> 'Tag',
+	'BBCODE_TAG_TOO_LONG'		=> 'The tag definition that you have entered is too long, please shorten your tag definition.',
 	'BBCODE_USAGE'				=> 'BBCode usage',
 	'BBCODE_USAGE_EXAMPLE'		=> '[colour={COLOR}]{TEXT}[/colour]<br /><br />[font={TEXT1}]{TEXT2}[/font]',
 	'BBCODE_USAGE_EXPLAIN'		=> 'Here you define how to use the bbcode. Replace any variable input by the corresponding token (%ssee below%s)',