diff --git a/spec/Middleware/MezzioSpec.php b/spec/Middleware/MezzioSpec.php
index 2dd8803e..3b340612 100644
--- a/spec/Middleware/MezzioSpec.php
+++ b/spec/Middleware/MezzioSpec.php
@@ -327,7 +327,7 @@
                 );
 
                 $request = $this->request;
-                $request  = $request->withHeader('X-Requested-With', 'XmlHttpRequest');
+                $request  = $request->withHeader('X-Requested-With', random_int(0, 1) !== 0 ? 'XMLHttpRequest' : 'XmlHttpRequest');
 
                 $handler  = Double::instance(['implements' => RequestHandlerInterface::class]);
                 allow($handler)->toReceive('handle')->with($request)->andRun(function (): never {
@@ -364,7 +364,7 @@
                 );
 
                 $request  = $this->request;
-                $request  = $request->withHeader('X-Requested-With', 'XmlHttpRequest');
+                $request  = $request->withHeader('X-Requested-With', random_int(0, 1) !== 0 ? 'XMLHttpRequest' : 'XmlHttpRequest');
 
                 $handler  = Double::instance(['implements' => RequestHandlerInterface::class]);
                 allow($handler)->toReceive('handle')->with($request)->andRun(function (): never {
@@ -401,7 +401,7 @@
                 );
 
                 $request  = $this->request;
-                $request  = $request->withHeader('X-Requested-With', 'XmlHttpRequest');
+                $request  = $request->withHeader('X-Requested-With', random_int(0, 1) !== 0 ? 'XMLHttpRequest' : 'XmlHttpRequest');
 
                 $handler  = Double::instance(['implements' => RequestHandlerInterface::class]);
                 allow($handler)->toReceive('handle')->with($request)->andRun(function (): never {
@@ -436,7 +436,7 @@
             );
 
             $request  = $this->request;
-            $request  = $request->withHeader('X-Requested-With', 'XmlHttpRequest');
+            $request  = $request->withHeader('X-Requested-With', random_int(0, 1) !== 0 ? 'XMLHttpRequest' : 'XmlHttpRequest');
 
             $handler  = Double::instance(['implements' => RequestHandlerInterface::class]);
             allow($handler)->toReceive('handle')->with($request)->andRun(function () use ($exception): never {
diff --git a/src/Middleware/Mezzio.php b/src/Middleware/Mezzio.php
index de44705f..6ba7e07a 100644
--- a/src/Middleware/Mezzio.php
+++ b/src/Middleware/Mezzio.php
@@ -23,6 +23,7 @@
 
 use function ErrorHeroModule\detectMessageContentType;
 use function ErrorHeroModule\isExcludedException;
+use function strcasecmp;
 
 final class Mezzio implements MiddlewareInterface
 {
@@ -101,7 +102,7 @@ private function showDefaultView(): Response|HtmlResponse
         /** @var  ServerRequestInterface $request */
         $request          = $this->request;
         $isXmlHttpRequest = $request->hasHeader('X-Requested-With')
-            && $request->getHeaderLine('X-Requested-With') === 'XmlHttpRequest';
+            && strcasecmp($request->getHeaderLine('X-Requested-With'), 'XMLHttpRequest') === 0;
 
         if (
             $isXmlHttpRequest &&