diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1405c54..4e42c85 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,26 @@
 
 All notable changes to this project will be documented in this file, in reverse chronological order by release.
 
+## 0.2.1 - 2017-06-13
+
+### Added
+
+- Nothing.
+
+### Deprecated
+
+- Nothing.
+
+### Removed
+
+- Nothing.
+
+### Fixed
+
+- [#5](https://github.com/weierophinney/problem-details/pull/5) updates the
+  response factory and middleware to treat lack of/empty `Accept` header values
+  as `*/*`, per RFC-7231 section 5.3.2.
+
 ## 0.2.0 - 2017-05-30
 
 ### Added
diff --git a/src/ProblemDetailsMiddleware.php b/src/ProblemDetailsMiddleware.php
index 6f15d39..f429e69 100644
--- a/src/ProblemDetailsMiddleware.php
+++ b/src/ProblemDetailsMiddleware.php
@@ -54,7 +54,7 @@ public function process(ServerRequestInterface $request, DelegateInterface $dele
 
     private function canActAsErrorHandler(ServerRequestInterface $request) : bool
     {
-        $accept = $request->getHeaderLine('Accept');
+        $accept = $request->getHeaderLine('Accept') ?: '*/*';
         if (empty($accept)) {
             return false;
         }
diff --git a/src/ProblemDetailsResponseFactory.php b/src/ProblemDetailsResponseFactory.php
index 7868a60..7c52ece 100644
--- a/src/ProblemDetailsResponseFactory.php
+++ b/src/ProblemDetailsResponseFactory.php
@@ -285,7 +285,7 @@ private function generateStream() : StreamInterface
 
     private function getResponseGenerator(ServerRequestInterface $request) : callable
     {
-        $accept    = $request->getHeaderLine('Accept', 'application/xhtml+xml');
+        $accept    = $request->getHeaderLine('Accept') ?: '*/*';
         $mediaType = (new Negotiator())->getBest($accept, self::NEGOTIATION_PRIORITIES);
 
         if (! $mediaType) {
diff --git a/test/ProblemDetailsMiddlewareTest.php b/test/ProblemDetailsMiddlewareTest.php
index 080e1b4..36338b5 100644
--- a/test/ProblemDetailsMiddlewareTest.php
+++ b/test/ProblemDetailsMiddlewareTest.php
@@ -26,6 +26,7 @@ protected function setUp()
     public function acceptHeaders()
     {
         return [
+            'empty'                    => [''],
             'application/xml'          => ['application/xml'],
             'application/vnd.api+xml'  => ['application/vnd.api+xml'],
             'application/json'         => ['application/json'],
diff --git a/test/ProblemDetailsResponseFactoryTest.php b/test/ProblemDetailsResponseFactoryTest.php
index f30372a..1293887 100644
--- a/test/ProblemDetailsResponseFactoryTest.php
+++ b/test/ProblemDetailsResponseFactoryTest.php
@@ -24,6 +24,7 @@ protected function setUp()
     public function acceptHeaders()
     {
         return [
+            'empty'                    => ['', 'application/problem+json'],
             'application/xml'          => ['application/xml', 'application/problem+xml'],
             'application/vnd.api+xml'  => ['application/vnd.api+xml', 'application/problem+xml'],
             'application/json'         => ['application/json', 'application/problem+json'],
@@ -36,7 +37,7 @@ public function acceptHeaders()
      */
     public function testCreateResponseCreatesExpectedType(string $header, string $expectedType)
     {
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn($header);
+        $this->request->getHeaderLine('Accept')->willReturn($header);
 
         $response = $this->factory->createResponse(
             $this->request->reveal(),
@@ -53,7 +54,7 @@ public function testCreateResponseCreatesExpectedType(string $header, string $ex
      */
     public function testCreateResponseFromThrowableCreatesExpectedType(string $header, string $expectedType)
     {
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn($header);
+        $this->request->getHeaderLine('Accept')->willReturn($header);
 
         $exception = new RuntimeException();
         $response = $this->factory->createResponseFromThrowable(
@@ -72,7 +73,7 @@ public function testCreateResponseFromThrowableCreatesExpectedTypeWithExtraInfor
         string $header,
         string $expectedType
     ) {
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn($header);
+        $this->request->getHeaderLine('Accept')->willReturn($header);
 
         $factory = new ProblemDetailsResponseFactory(ProblemDetailsResponseFactory::INCLUDE_THROWABLE_DETAILS);
 
@@ -98,7 +99,7 @@ public function testCreateResponseFromThrowableWillPullDetailsFromProblemDetails
         $e->getType()->willReturn('https://example.com/api/doc/invalid-client-request');
         $e->getAdditionalData()->willReturn(['foo' => 'bar']);
 
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn('application/json');
+        $this->request->getHeaderLine('Accept')->willReturn('application/json');
 
         $factory = new ProblemDetailsResponseFactory();
 
@@ -121,7 +122,7 @@ public function testCreateResponseFromThrowableWillPullDetailsFromProblemDetails
 
     public function testFactoryRaisesExceptionIfBodyFactoryDoesNotReturnStream()
     {
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn('application/json');
+        $this->request->getHeaderLine('Accept')->willReturn('application/json');
 
         $factory = new ProblemDetailsResponseFactory(false, null, null, function () {
             return null;
@@ -133,7 +134,7 @@ public function testFactoryRaisesExceptionIfBodyFactoryDoesNotReturnStream()
 
     public function testFactoryGeneratesXmlResponseIfNegotiationFails()
     {
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn('text/plain');
+        $this->request->getHeaderLine('Accept')->willReturn('text/plain');
 
         $response = $this->factory->createResponse(
             $this->request->reveal(),
@@ -147,7 +148,7 @@ public function testFactoryGeneratesXmlResponseIfNegotiationFails()
 
     public function testFactoryRendersPreviousExceptionsInDebugMode()
     {
-        $this->request->getHeaderLine('Accept', 'application/xhtml+xml')->willReturn('application/json');
+        $this->request->getHeaderLine('Accept')->willReturn('application/json');
 
         $first = new RuntimeException('first', 101010);
         $second = new RuntimeException('second', 101011, $first);