diff --git a/src/ErrorHandler/ErrorCatcher.php b/src/ErrorHandler/ErrorCatcher.php
index <HASH>..<HASH> 100644
--- a/src/ErrorHandler/ErrorCatcher.php
+++ b/src/ErrorHandler/ErrorCatcher.php
@@ -113,7 +113,7 @@ final class ErrorCatcher implements MiddlewareInterface
     private function getContentType(ServerRequestInterface $request): string
     {
         try {
-            foreach (HeaderHelper::getSortedAcceptTypes($request->getHeader('accept')) as $header) {
+            foreach (HeaderHelper::getSortedAcceptTypes($request->getHeader(Header::ACCEPT)) as $header) {
                 if (array_key_exists($header, $this->renderers)) {
                     return $header;
                 }
Use header constant in ErrorCatcher