diff --git a/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverter.php b/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverter.php
index 9ec78c509..026ff7a8a 100644
--- a/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverter.php
+++ b/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverter.php
@@ -16,7 +16,7 @@ use DateTimeImmutable;
 use LogicException;
 use UnexpectedValueException;
 
-class RollingDateConverter
+class RollingDateConverter implements RollingDateConverterInterface
 {
     public function convert(RollingDate $rollingDate): DateTimeImmutable
     {
diff --git a/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverterInterface.php b/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverterInterface.php
new file mode 100644
index 000000000..b20a5ced2
--- /dev/null
+++ b/src/Bundle/ChillMainBundle/Service/RollingDate/RollingDateConverterInterface.php
@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\MainBundle\Service\RollingDate;
+
+use DateTimeImmutable;
+
+interface RollingDateConverterInterface
+{
+    public function convert(RollingDate $rollingDate): DateTimeImmutable;
+}