diff --git a/core/functions.php b/core/functions.php
index 6e91cd7..1a48d54 100644
--- a/core/functions.php
+++ b/core/functions.php
@@ -375,12 +375,10 @@ function cf7a_maybe_split_mail_meta( $posted_data, $message_tag, $explode_patter
  * @return array $num_array The unsigned integer array.
  */
 function cf7a_str_array_to_uint_array( $str_array ) {
-	$num_array = array();
-	foreach ( $str_array as $value ) {
-		preg_match( '/^[0-9]+$/', esc_attr( $value ), $matches );
-		if ( $matches[0] ) {
-			$num_array[] = intval( $matches[0] );
+	return array_filter(
+		$str_array,
+		function ( $value ) {
+			return is_numeric( $value ) && $value > 0 && intval( $value ) == $value;
 		}
-	}
-	return $num_array;
+	);
 }