diff --git a/RouteDescriber/FosRestDescriber.php b/RouteDescriber/FosRestDescriber.php
index 626f6a7..9d39899 100644
--- a/RouteDescriber/FosRestDescriber.php
+++ b/RouteDescriber/FosRestDescriber.php
@@ -107,7 +107,7 @@ final class FosRestDescriber implements RouteDescriberInterface
         if ($requirements instanceof Constraint && !$requirements instanceof Regex) {
             if ($requirements instanceof DateTime) {
                 // As defined per RFC3339
-                if (\DateTimeInterface::RFC3339 === $requirements->format || 'c' === $requirements->format) {
+                if (\DateTime::RFC3339 === $requirements->format || 'c' === $requirements->format) {
                     return 'date-time';
                 } elseif ('Y-m-d' === $requirements->format) {
                     return 'date';