diff --git a/src/Http/RequestArgumentsResolver.php b/src/Http/RequestArgumentsResolver.php
new file mode 100644
index 00000000..cc876401
--- /dev/null
+++ b/src/Http/RequestArgumentsResolver.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace League\Glide\Http;
+
+use InvalidArgumentException;
+use Symfony\Component\HttpFoundation\Request;
+
+class RequestArgumentsResolver
+{
+    /**
+     * Resolve request object.
+     * @param  array   $args Array of supplied arguments.
+     * @return Request The request object.
+     */
+    public function getRequest($args)
+    {
+        if (isset($args[0]) and $args[0] instanceof Request) {
+            return $args[0];
+        }
+
+        if (isset($args[0]) and is_string($args[0])) {
+            $path = $args[0];
+            $params = [];
+
+            if (isset($args[1]) and is_array($args[1])) {
+                $params = $args[1];
+            }
+
+            return RequestFactory::create($path, $params);
+        }
+
+        throw new InvalidArgumentException('Not a valid path or Request object.');
+    }
+}
diff --git a/src/Http/Signature.php b/src/Http/Signature.php
index 12825376..186e1d67 100644
--- a/src/Http/Signature.php
+++ b/src/Http/Signature.php
@@ -34,11 +34,13 @@ public function addSignature($path, array $params)
 
     /**
      * Validate a request signature.
-     * @param  Request            $request The request object.
+     * @param  mixed
      * @throws SignatureException
      */
-    public function validateRequest(Request $request)
+    public function validateRequest()
     {
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
+
         if (is_null($request->get('s'))) {
             throw new SignatureException('Signature is missing.');
         }
diff --git a/src/Http/SignatureInterface.php b/src/Http/SignatureInterface.php
index 94b96350..adc9cd18 100644
--- a/src/Http/SignatureInterface.php
+++ b/src/Http/SignatureInterface.php
@@ -16,8 +16,8 @@ public function addSignature($path, array $params);
 
     /**
      * Validate a request signature.
-     * @param  Request            $request The request object.
+     * @param  mixed
      * @throws SignatureException
      */
-    public function validateRequest(Request $request);
+    public function validateRequest();
 }
diff --git a/src/Server.php b/src/Server.php
index 21e09030..cc7aec06 100644
--- a/src/Server.php
+++ b/src/Server.php
@@ -2,13 +2,12 @@
 
 namespace League\Glide;
 
-use InvalidArgumentException;
 use League\Flysystem\FileExistsException;
 use League\Flysystem\FilesystemInterface;
 use League\Glide\Api\ApiInterface;
 use League\Glide\Filesystem\FilesystemException;
 use League\Glide\Http\NotFoundException;
-use League\Glide\Http\RequestFactory;
+use League\Glide\Http\RequestArgumentsResolver;
 use League\Glide\Http\ResponseFactory;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\StreamedResponse;
@@ -57,7 +56,7 @@ class Server
      * @param FilesystemInterface|null $cache  The cache file system.
      * @param ApiInterface             $api    The image manipulation API.
      */
-    public function __construct(FilesystemInterface $source, $cache, ApiInterface $api)
+    public function __construct(FilesystemInterface $source, FilesystemInterface $cache = null, ApiInterface $api)
     {
         $this->setSource($source);
         $this->setCache($cache);
@@ -108,7 +107,7 @@ public function getSourcePathPrefix()
      */
     public function getSourcePath()
     {
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         $path = trim($request->getPathInfo(), '/');
 
@@ -134,7 +133,7 @@ public function getSourcePath()
      */
     public function sourceFileExists()
     {
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         return $this->source->has($this->getSourcePath($request));
     }
@@ -143,7 +142,7 @@ public function sourceFileExists()
      * Set the cache file system.
      * @param FilesystemInterface|null $cache The cache file system.
      */
-    public function setCache($cache)
+    public function setCache(FilesystemInterface $cache = null)
     {
         $this->cache = $cache;
     }
@@ -182,7 +181,7 @@ public function getCachePathPrefix()
      */
     public function getCachePath()
     {
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         $path = md5($this->getSourcePath($request).'?'.http_build_query($request->query->all()));
 
@@ -204,7 +203,7 @@ public function cacheFileExists()
             return false;
         }
 
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         return $this->cache->has($this->getCachePath($request));
     }
@@ -252,7 +251,7 @@ public function getBaseUrl()
      */
     public function outputImage()
     {
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         $this->makeImage($request);
 
@@ -274,7 +273,7 @@ public function outputImage()
      */
     public function getImageResponse()
     {
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         $this->makeImage($request);
 
@@ -288,7 +287,7 @@ public function getImageResponse()
      */
     public function makeImage()
     {
-        $request = $this->resolveRequestObject(func_get_args());
+        $request = (new RequestArgumentsResolver())->getRequest(func_get_args());
 
         if ($this->cacheFileExists($request) === true) {
             return $request;
@@ -310,62 +309,36 @@ public function makeImage()
             );
         }
 
-        try {
-            $written = $this->writeCache($request, $source);
-        } catch (FileExistsException $exception) {
-            // Cache file failed to write. Fail silently.
-            return $request;
-        }
-
-        if ($written === false) {
-            throw new FilesystemException(
-                'Could not write the image `'.$this->getCachePath($request).'`.'
-            );
+        if ($this->cache) {
+            $this->writeCache($request, $source);
         }
 
         return $request;
     }
 
-    /**
-     * Resolve request object.
-     * @param  array   $args Array of supplied arguments.
-     * @return Request The request object.
-     */
-    protected function resolveRequestObject($args)
-    {
-        if (isset($args[0]) and $args[0] instanceof Request) {
-            return $args[0];
-        }
-
-        if (isset($args[0]) and is_string($args[0])) {
-            $path = $args[0];
-            $params = [];
-
-            if (isset($args[1]) and is_array($args[1])) {
-                $params = $args[1];
-            }
-
-            return RequestFactory::create($path, $params);
-        }
-
-        throw new InvalidArgumentException('Not a valid path or Request object.');
-    }
-
     /**
      * Write the cache file if caching is enabled.
-     * @param Request $request
-     * @param string  $source
+     * @param  Request $request
+     * @param  string  $source
      * @return mixed
      */
-    private function writeCache(Request $request, $source)
+    protected function writeCache(Request $request, $source)
     {
-        if ($this->cache === null) {
-            return null;
-        }
+        try {
+            $written = $this->cache->write(
+                $this->getCachePath($request),
+                $this->api->run($request, $source)
+            );
 
-        return $this->cache->write(
-            $this->getCachePath($request),
-            $this->api->run($request, $source)
-        );
+            if ($written === false) {
+                throw new FilesystemException(
+                    'Could not write the image `'.$this->getCachePath($request).'`.'
+                );
+            }
+        } catch (FileExistsException $exception) {
+            // This edge case occurs when the target already exists
+            // because it's currently be written to disk in another
+            // request. It's best to just fail silently.
+        }
     }
 }
diff --git a/tests/Http/RequestArgumentsResolverTest.php b/tests/Http/RequestArgumentsResolverTest.php
new file mode 100644
index 00000000..97925132
--- /dev/null
+++ b/tests/Http/RequestArgumentsResolverTest.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace League\Glide\Http;
+
+class RequestArgumentsResolverTest extends \PHPUnit_Framework_TestCase
+{
+    private $resolver;
+
+    public function setUp()
+    {
+        $this->resolver = new RequestArgumentsResolver();
+    }
+
+    public function testCreateRequestArgumentsResolver()
+    {
+        $this->assertInstanceOf(
+            'League\Glide\Http\RequestArgumentsResolver',
+            $this->resolver
+        );
+    }
+
+    public function testRequestObjectArg()
+    {
+        $request = $this->resolver->getRequest([
+            RequestFactory::create('image.jpg', ['w' => 100]),
+        ]);
+
+        $this->assertEquals('image.jpg', $request->getPathInfo());
+        $this->assertEquals(['w' => 100], $request->query->all());
+        $this->assertInstanceOf('Symfony\Component\HttpFoundation\Request', $request);
+    }
+
+    public function testRequestParamsArgs()
+    {
+        $request = $this->resolver->getRequest([
+            'image.jpg', ['w' => 100],
+        ]);
+
+        $this->assertEquals('image.jpg', $request->getPathInfo());
+        $this->assertEquals(['w' => 100], $request->query->all());
+        $this->assertInstanceOf('Symfony\Component\HttpFoundation\Request', $request);
+    }
+
+    public function testInvalidArgs()
+    {
+        $this->setExpectedException(
+            'InvalidArgumentException',
+            'Not a valid path or Request object.'
+        );
+
+        $this->resolver->getRequest([]);
+    }
+}