diff --git a/lib/Jejik/MT940/Parser/AbstractParser.php b/lib/Jejik/MT940/Parser/AbstractParser.php
index bc3f28e..7ac3b37 100644
--- a/lib/Jejik/MT940/Parser/AbstractParser.php
+++ b/lib/Jejik/MT940/Parser/AbstractParser.php
@@ -244,7 +244,7 @@ protected function splitTransactions(string $text): array
      *
      * @throws \Exception
      */
-    protected function statement(string $text): ?Statement
+    protected function statement(string $text): ?StatementInterface
     {
         $text = trim($text);
         if (($pos = strpos($text, ':20:')) === false) {
@@ -272,7 +272,7 @@ protected function statementHeader(string $text): void
      *
      * @throws \Exception
      */
-    protected function statementBody(string $text): ?Statement
+    protected function statementBody(string $text): ?StatementInterface
     {
         $accountNumber = $this->accountNumber($text);
         $accountCurrency = $this->accountCurrency($text);