diff --git a/phpBB/includes/db/dbal.php b/phpBB/includes/db/dbal.php
index 8dbcd73b58..fded27a001 100644
--- a/phpBB/includes/db/dbal.php
+++ b/phpBB/includes/db/dbal.php
@@ -311,7 +311,7 @@ class dbal
 	*/
 	function sql_concatenate($expr1, $expr2)
 	{
-		return 'CONCAT(' . $expr1 . ', ' . $expr2 . ')';
+		return $expr1 . ' || ' . $expr2;
 	}
 
 	/**
diff --git a/phpBB/includes/db/firebird.php b/phpBB/includes/db/firebird.php
index d6b16d0342..7709e8fdf5 100644
--- a/phpBB/includes/db/firebird.php
+++ b/phpBB/includes/db/firebird.php
@@ -110,14 +110,6 @@ class dbal_firebird extends dbal
 		return ($raw) ? '2.1' : 'Firebird/Interbase';
 	}
 
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_concatenate($expr1, $expr2)
-	{
-		return $expr1 . ' || ' . $expr2;
-	}
-
 	/**
 	* SQL Transaction
 	* @access private
diff --git a/phpBB/includes/db/mysql.php b/phpBB/includes/db/mysql.php
index eb38e3e913..3cda5cc1e0 100644
--- a/phpBB/includes/db/mysql.php
+++ b/phpBB/includes/db/mysql.php
@@ -119,6 +119,14 @@ class dbal_mysql extends dbal
 		return ($raw) ? $this->sql_server_version : 'MySQL ' . $this->sql_server_version;
 	}
 
+	/**
+	* {@inheritDoc}
+	*/
+	function sql_concatenate($expr1, $expr2)
+	{
+		return 'CONCAT(' . $expr1 . ', ' . $expr2 . ')';
+	}
+
 	/**
 	* SQL Transaction
 	* @access private
diff --git a/phpBB/includes/db/mysqli.php b/phpBB/includes/db/mysqli.php
index 4210a58002..e3828d9599 100644
--- a/phpBB/includes/db/mysqli.php
+++ b/phpBB/includes/db/mysqli.php
@@ -122,6 +122,14 @@ class dbal_mysqli extends dbal
 		return ($raw) ? $this->sql_server_version : 'MySQL(i) ' . $this->sql_server_version;
 	}
 
+	/**
+	* {@inheritDoc}
+	*/
+	function sql_concatenate($expr1, $expr2)
+	{
+		return 'CONCAT(' . $expr1 . ', ' . $expr2 . ')';
+	}
+
 	/**
 	* SQL Transaction
 	* @access private
diff --git a/phpBB/includes/db/postgres.php b/phpBB/includes/db/postgres.php
index a31181b4d4..bf22cffafa 100644
--- a/phpBB/includes/db/postgres.php
+++ b/phpBB/includes/db/postgres.php
@@ -154,14 +154,6 @@ class dbal_postgres extends dbal
 		return ($raw) ? $this->sql_server_version : 'PostgreSQL ' . $this->sql_server_version;
 	}
 
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_concatenate($expr1, $expr2)
-	{
-		return $expr1 . ' || ' . $expr2;
-	}
-
 	/**
 	* SQL Transaction
 	* @access private
diff --git a/phpBB/includes/db/sqlite.php b/phpBB/includes/db/sqlite.php
index 6eb77e5a70..86bfa75a13 100644
--- a/phpBB/includes/db/sqlite.php
+++ b/phpBB/includes/db/sqlite.php
@@ -72,14 +72,6 @@ class dbal_sqlite extends dbal
 		return ($raw) ? $this->sql_server_version : 'SQLite ' . $this->sql_server_version;
 	}
 
-	/**
-	* {@inheritDoc}
-	*/
-	function sql_concatenate($expr1, $expr2)
-	{
-		return $expr1 . ' || ' . $expr2;
-	}
-
 	/**
 	* SQL Transaction
 	* @access private