-if( empty( $wgLanguageCode ) ) {
- # Quick hack for upgrades where this will be blank,
- # and it's not handled right. Set to default.
+# Validate $wgLanguageCode, which will soon be sent to an eval()
+if( empty( $wgLanguageCode ) || !preg_match( '/^[a-z\-]*$/', $wgLanguageCode ) ) {