diff --git a/src/Routing/ResponsePrep/ContentLengthPrep.php b/src/Routing/Hook/ContentLengthHook.php
similarity index 89%
rename from src/Routing/ResponsePrep/ContentLengthPrep.php
rename to src/Routing/Hook/ContentLengthHook.php
index 863fd7a..fc9c554 100644
--- a/src/Routing/ResponsePrep/ContentLengthPrep.php
+++ b/src/Routing/Hook/ContentLengthHook.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace WellRESTed\Routing\ResponsePrep;
+namespace WellRESTed\Routing\Hook;
 
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
@@ -13,7 +13,7 @@ use WellRESTed\Routing\MiddlewareInterface;
  * - Response does not have a Tranfser-encoding: chunked header
  * - Response body stream reports a size
  */
-class ContentLengthPrep implements MiddlewareInterface
+class ContentLengthHook implements MiddlewareInterface
 {
     public function dispatch(ServerRequestInterface $request, ResponseInterface &$response)
     {
diff --git a/src/Routing/ResponsePrep/HeadPrep.php b/src/Routing/Hook/HeadHook.php
similarity index 86%
rename from src/Routing/ResponsePrep/HeadPrep.php
rename to src/Routing/Hook/HeadHook.php
index c1a5001..d89bfd9 100644
--- a/src/Routing/ResponsePrep/HeadPrep.php
+++ b/src/Routing/Hook/HeadHook.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace WellRESTed\Routing\ResponsePrep;
+namespace WellRESTed\Routing\Hook;
 
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
@@ -10,7 +10,7 @@ use WellRESTed\Routing\MiddlewareInterface;
 /**
  * Removes the body of a response to a HEAD request.
  */
-class HeadPrep implements MiddlewareInterface
+class HeadHook implements MiddlewareInterface
 {
     public function dispatch(ServerRequestInterface $request, ResponseInterface &$response)
     {
diff --git a/test/tests/unit/Routing/ResponsePrep/ContentLengthPrepTest.php b/test/tests/unit/Routing/Hook/ContentLengthHookTest.php
similarity index 61%
rename from test/tests/unit/Routing/ResponsePrep/ContentLengthPrepTest.php
rename to test/tests/unit/Routing/Hook/ContentLengthHookTest.php
index 91a46c8..5c8f8e3 100644
--- a/test/tests/unit/Routing/ResponsePrep/ContentLengthPrepTest.php
+++ b/test/tests/unit/Routing/Hook/ContentLengthHookTest.php
@@ -1,14 +1,14 @@
 <?php
 
-namespace WellRESTed\Test\Unit\Routing;
+namespace WellRESTed\Test\Unit\Routing\Hook;
 
 use Prophecy\Argument;
-use WellRESTed\Routing\ResponsePrep\ContentLengthPrep;
+use WellRESTed\Routing\Hook\ContentLengthHook;
 
 /**
- * @covers WellRESTed\Routing\ResponsePrep\ContentLengthPrep
+ * @covers WellRESTed\Routing\Hook\ContentLengthHook
  */
-class ContentLengthPrepTest extends \PHPUnit_Framework_TestCase
+class ContentLengthHookTest extends \PHPUnit_Framework_TestCase
 {
     private $request;
     private $response;
@@ -22,22 +22,41 @@ class ContentLengthPrepTest extends \PHPUnit_Framework_TestCase
         $this->request = $this->prophesize('Psr\Http\Message\ServerRequestInterface');
         $this->response = $this->prophesize('Psr\Http\Message\ResponseInterface');
         $this->response->getBody()->willReturn($this->body->reveal());
-        $this->response->withHeader(Argument::cetera())->willReturn($this->response->reveal());
+        $this->response->withHeader(Argument::cetera())->will(
+            function () {
+                $this->hasHeader("Content-length")->willReturn(true);
+                return $this;
+            }
+        );
     }
 
-    public function testAddContentLengthHeader()
+    public function testAddsContentLengthHeader()
     {
         $this->response->hasHeader("Content-length")->willReturn(false);
         $this->response->getHeaderLine("Transfer-encoding")->willReturn("");
 
         $request = $this->request->reveal();
         $response = $this->response->reveal();
-        $prep = new ContentLengthPrep();
-        $prep->dispatch($request, $response);
+        $hook = new ContentLengthHook();
+        $hook->dispatch($request, $response);
 
         $this->response->withHeader("Content-length", 1024)->shouldHaveBeenCalled();
     }
 
+    public function testMultipleDispatchesHaveNoEffect()
+    {
+        $this->response->hasHeader("Content-length")->willReturn(false);
+        $this->response->getHeaderLine("Transfer-encoding")->willReturn("");
+
+        $request = $this->request->reveal();
+        $response = $this->response->reveal();
+        $hook = new ContentLengthHook();
+        $hook->dispatch($request, $response);
+        $hook->dispatch($request, $response);
+
+        $this->response->withHeader("Content-length", 1024)->shouldHaveBeenCalledTimes(1);
+    }
+
     public function testDoesNotAddHeaderWhenContentLenghtIsAlreadySet()
     {
         $this->response->hasHeader("Content-length")->willReturn(true);
@@ -45,8 +64,8 @@ class ContentLengthPrepTest extends \PHPUnit_Framework_TestCase
 
         $request = $this->request->reveal();
         $response = $this->response->reveal();
-        $prep = new ContentLengthPrep();
-        $prep->dispatch($request, $response);
+        $hook = new ContentLengthHook();
+        $hook->dispatch($request, $response);
 
         $this->response->withHeader(Argument::cetera())->shouldNotHaveBeenCalled();
     }
@@ -58,8 +77,8 @@ class ContentLengthPrepTest extends \PHPUnit_Framework_TestCase
 
         $request = $this->request->reveal();
         $response = $this->response->reveal();
-        $prep = new ContentLengthPrep();
-        $prep->dispatch($request, $response);
+        $hook = new ContentLengthHook();
+        $hook->dispatch($request, $response);
 
         $this->response->withHeader(Argument::cetera())->shouldNotHaveBeenCalled();
     }
@@ -72,8 +91,8 @@ class ContentLengthPrepTest extends \PHPUnit_Framework_TestCase
 
         $request = $this->request->reveal();
         $response = $this->response->reveal();
-        $prep = new ContentLengthPrep();
-        $prep->dispatch($request, $response);
+        $hook = new ContentLengthHook();
+        $hook->dispatch($request, $response);
 
         $this->response->withHeader(Argument::cetera())->shouldNotHaveBeenCalled();
     }
diff --git a/test/tests/unit/Routing/ResponsePrep/HeadPrepTest.php b/test/tests/unit/Routing/Hook/HeadHookTest.php
similarity index 63%
rename from test/tests/unit/Routing/ResponsePrep/HeadPrepTest.php
rename to test/tests/unit/Routing/Hook/HeadHookTest.php
index 9946188..6506f74 100644
--- a/test/tests/unit/Routing/ResponsePrep/HeadPrepTest.php
+++ b/test/tests/unit/Routing/Hook/HeadHookTest.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace WellRESTed\Test\Unit\Routing;
+namespace WellRESTed\Test\Unit\Routing\Hook;
 
 use Prophecy\Argument;
-use WellRESTed\Routing\ResponsePrep\HeadPrep;
+use WellRESTed\Routing\Hook\HeadHook;
 
 /**
- * @covers WellRESTed\Routing\ResponsePrep\HeadPrep
+ * @covers WellRESTed\Routing\Hook\HeadHook
  * @uses WellRESTed\Message\NullStream
  */
-class HeadPrepTest extends \PHPUnit_Framework_TestCase
+class HeadHookTest extends \PHPUnit_Framework_TestCase
 {
     private $request;
     private $response;
@@ -34,18 +34,29 @@ class HeadPrepTest extends \PHPUnit_Framework_TestCase
         $this->request->getMethod()->willReturn("HEAD");
         $request = $this->request->reveal();
         $response = $this->response->reveal();
-        $prep = new HeadPrep();
-        $prep->dispatch($request, $response);
+        $hook = new HeadHook();
+        $hook->dispatch($request, $response);
         $this->assertSame(0, $response->getBody()->getSize());
     }
 
+    public function testMultipleDispatchesHaveNoEffect()
+    {
+        $this->request->getMethod()->willReturn("HEAD");
+        $request = $this->request->reveal();
+        $response = $this->response->reveal();
+        $hook = new HeadHook();
+        $hook->dispatch($request, $response);
+        $hook->dispatch($request, $response);
+        $this->response->withBody(Argument::any())->shouldHaveBeenCalledTimes(1);
+    }
+
     public function testDoesNotReplaceBodyForNonHeadRequests()
     {
         $this->request->getMethod()->willReturn("GET");
         $request = $this->request->reveal();
         $response = $this->response->reveal();
-        $prep = new HeadPrep();
-        $prep->dispatch($request, $response);
+        $hook = new HeadHook();
+        $hook->dispatch($request, $response);
         $this->response->withBody(Argument::any())->shouldNotHaveBeenCalled();
     }
 }