diff --git a/src/Handshake/RequestVerifier.php b/src/Handshake/RequestVerifier.php
index dbce9a9..9e192c5 100644
--- a/src/Handshake/RequestVerifier.php
+++ b/src/Handshake/RequestVerifier.php
@@ -119,10 +119,10 @@ class RequestVerifier {
 
     /**
      * Verify the version passed matches this RFC
-     * @param string|int $versionHeader MUST equal 13|"13"
+     * @param string[] $versionHeader MUST equal ["13"]
      * @return bool
      */
-    public function verifyVersion($versionHeader) {
+    public function verifyVersion(array $versionHeader) {
         return (1 === count($versionHeader) && static::VERSION === (int)$versionHeader[0]);
     }
 
diff --git a/src/Handshake/ResponseVerifier.php b/src/Handshake/ResponseVerifier.php
index 38904e8..453f9d6 100644
--- a/src/Handshake/ResponseVerifier.php
+++ b/src/Handshake/ResponseVerifier.php
@@ -51,7 +51,13 @@ class ResponseVerifier {
     }
 
     public function verifySubProtocol(array $requestHeader, array $responseHeader) {
-        return 0 === count($responseHeader) || count(array_intersect($responseHeader, $requestHeader)) > 0;
+        if (0 === count($responseHeader)) {
+            return true;
+        }
+
+        $requestedProtocols = array_map('trim', explode(',', implode(',', $requestHeader)));
+
+        return count($responseHeader) === 1 && count(array_intersect($responseHeader, $requestedProtocols)) === 1;
     }
 
     public function verifyExtensions(array $requestHeader, array $responseHeader) {
diff --git a/tests/unit/Handshake/ResponseVerifierTest.php b/tests/unit/Handshake/ResponseVerifierTest.php
index 0ca18e3..9a1459b 100644
--- a/tests/unit/Handshake/ResponseVerifierTest.php
+++ b/tests/unit/Handshake/ResponseVerifierTest.php
@@ -21,17 +21,19 @@ class ResponseVerifierTest extends TestCase {
     public static function subProtocolsProvider() {
         return [
             [true,  ['a'], ['a']]
-          , [true,  ['b', 'a'], ['c', 'd', 'a']]
-          , [false, ['a', 'b', 'c'], ['d']]
+          , [true,  ['c', 'd', 'a'], ['a']]
+          , [true,  ['c, a', 'd'], ['a']]
           , [true,  [], []]
           , [true,  ['a', 'b'], []]
+          , [false, ['c', 'd', 'a'], ['b', 'a']]
+          , [false, ['a', 'b', 'c'], ['d']]
         ];
     }
 
     /**
      * @dataProvider subProtocolsProvider
      */
-    public function testVerifySubProtocol($expected, $response, $request) {
-        $this->assertEquals($expected, $this->_v->verifySubProtocol($response, $request));
+    public function testVerifySubProtocol($expected, $request, $response) {
+        $this->assertEquals($expected, $this->_v->verifySubProtocol($request, $response));
     }
 }