diff --git a/RequestMatcher.php b/RequestMatcher.php
index 9a4a2a137..82be2d868 100644
--- a/RequestMatcher.php
+++ b/RequestMatcher.php
@@ -167,7 +167,11 @@ public function matches(Request $request)
         }
 
         foreach ($this->attributes as $key => $pattern) {
-            if (!preg_match('{'.$pattern.'}', $request->attributes->get($key))) {
+            $requestAttribute = $request->attributes->get($key);
+            if (!\is_string($requestAttribute)) {
+                return false;
+            }
+            if (!preg_match('{'.$pattern.'}', $requestAttribute)) {
                 return false;
             }
         }
diff --git a/Tests/RequestMatcherTest.php b/Tests/RequestMatcherTest.php
index 57e9c3d30..e913a60c8 100644
--- a/Tests/RequestMatcherTest.php
+++ b/Tests/RequestMatcherTest.php
@@ -163,4 +163,17 @@ public function testAttributes()
         $matcher->matchAttribute('foo', 'babar');
         $this->assertFalse($matcher->matches($request));
     }
+
+    public function testAttributesWithClosure()
+    {
+        $matcher = new RequestMatcher();
+
+        $request = Request::create('/admin/foo');
+        $request->attributes->set('_controller', function () {
+            return new Response('foo');
+        });
+
+        $matcher->matchAttribute('_controller', 'babar');
+        $this->assertFalse($matcher->matches($request));
+    }
 }