diff --git a/src/ApiProblem.php b/src/ApiProblem.php
index e97a43d..d85be77 100644
--- a/src/ApiProblem.php
+++ b/src/ApiProblem.php
@@ -140,6 +140,14 @@ public function __construct($status, $detail, $type = null, $title = null, array
             }
         }
 
+        // Ensure a valid HTTP status
+        if (! is_numeric($status)
+            || ($status < 100)
+            || ($status > 599)
+        ) {
+            $status = 500;
+        }
+
         $this->status = $status;
         $this->detail = $detail;
         $this->title  = $title;
diff --git a/src/Listener/ApiProblemListener.php b/src/Listener/ApiProblemListener.php
index 06009fb..c7f6e66 100644
--- a/src/Listener/ApiProblemListener.php
+++ b/src/Listener/ApiProblemListener.php
@@ -157,21 +157,13 @@ public function onDispatchError(MvcEvent $e)
 
         // Marshall an ApiProblem and view model based on the exception
         $exception = $e->getParam('exception');
-        if ($exception instanceof ProblemExceptionInterface) {
-            $problem = new ApiProblem($exception->getCode(), $exception);
-        } elseif ($exception instanceof \Exception) {
-            $status = $exception->getCode();
-            if (0 === $status) {
-                $status = 500;
-            }
-            $problem = new ApiProblem($status, $exception);
-        } else {
+        if (! $exception instanceof \Exception) {
             // If it's not an exception, do not know what to do.
             return;
         }
 
         $e->stopPropagation();
-        $response = new ApiProblemResponse($problem);
+        $response = new ApiProblemResponse(new ApiProblem($exception->getCode(), $exception));
         $e->setResponse($response);
         return $response;
     }
diff --git a/test/ApiProblemResponseTest.php b/test/ApiProblemResponseTest.php
index 847941f..b587fb3 100644
--- a/test/ApiProblemResponseTest.php
+++ b/test/ApiProblemResponseTest.php
@@ -63,6 +63,6 @@ public function testComposeApiProblemIsAccessible()
     public function testOverridesReasonPhraseIfStatusCodeIsUnknown()
     {
         $response = new ApiProblemResponse(new ApiProblem(7, 'Random error'));
-        $this->assertContains('Unknown', $response->getReasonPhrase());
+        $this->assertContains('Internal Server Error', $response->getReasonPhrase());
     }
 }
diff --git a/test/ApiProblemTest.php b/test/ApiProblemTest.php
index c0e13ec..515dc05 100644
--- a/test/ApiProblemTest.php
+++ b/test/ApiProblemTest.php
@@ -215,4 +215,26 @@ public function testUsesAdditionalDetailsFromExceptionWhenProvided()
         $this->assertArrayHasKey('foo', $payload);
         $this->assertEquals('bar', $payload['foo']);
     }
+
+    public function invalidStatusCodes()
+    {
+        return array(
+            '-1'  => array(-1),
+            '0'   => array(0),
+            '7'   => array(7),  // reported
+            '14'  => array(14), // observed
+            '600' => array(600),
+        );
+    }
+
+    /**
+     * @dataProvider invalidStatusCodes
+     * @group zf-apigility-118
+     */
+    public function testInvalidHttpStatusCodesAreCastTo500($code)
+    {
+        $e = new \Exception('Testing', $code);
+        $problem = new ApiProblem($code, $e);
+        $this->assertEquals(500, $problem->status);
+    }
 }