diff --git a/includes/database/mysql/database.inc b/includes/database/mysql/database.inc
index 0b84f27..f266a50 100644
--- a/includes/database/mysql/database.inc
+++ b/includes/database/mysql/database.inc
@@ -47,10 +47,15 @@ class DatabaseConnection_mysql extends DatabaseConnection {
     );
     $connection_options['pdo'] += array(
       // So we don't have to mess around with cursors and unbuffered queries by default.
-      PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
+      \PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
       // Because MySQL's prepared statements skip the query cache, because it's dumb.
-      PDO::ATTR_EMULATE_PREPARES => TRUE,
+      \PDO::ATTR_EMULATE_PREPARES => TRUE,
     );
+    if (defined('\PDO::MYSQL_ATTR_MULTI_STATEMENTS')) {
+      // An added connection option in PHP 5.5.21+ to optionally limit SQL to a
+      // single statement like mysqli.
+      $connection_options['pdo'] += array(\PDO::MYSQL_ATTR_MULTI_STATEMENTS => FALSE);
+    }
 
     parent::__construct($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);
 
@@ -78,8 +83,10 @@ class DatabaseConnection_mysql extends DatabaseConnection {
     $connection_options['init_commands'] += array(
       'sql_mode' => "SET sql_mode = 'ANSI,STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER'",
     );
-    // Set connection options.
-    $this->exec(implode('; ', $connection_options['init_commands']));
+    // Execute initial commands.
+    foreach ($connection_options['init_commands'] as $sql) {
+      $this->exec($sql);
+    }
   }
 
   public function __destruct() {