Index: library/Zend/Controller/Router/Rewrite.php
===================================================================
--- library/Zend/Controller/Router/Rewrite.php  (revision 24077)
+++ library/Zend/Controller/Router/Rewrite.php  (working copy)
@@ -450,6 +450,11 @@
      */
     public function assemble($userParams, $name = null, $reset = false, $encode = true)
     {
+        if (!is_array($userParams)) {
+            require_once 'Zend/Controller/Router/Exception.php';
+            throw new Zend_Controller_Router_Exception('userParams must be an array');
+        }
+
         if ($name == null) {
             try {
                 $name = $this->getCurrentRouteName();
Index: tests/Zend/Controller/Router/RewriteTest.php
===================================================================
--- tests/Zend/Controller/Router/RewriteTest.php        (revision 24077)
+++ tests/Zend/Controller/Router/RewriteTest.php        (working copy)
@@ -756,6 +756,15 @@
             $this->_router->assemble($params)
         );
     }
+
+    /**
+     * @group ZF-11393
+     * @expectedException Zend_Controller_Router_Exception
+     */
+    public function testCallingAssembleWithNullArgumentShouldThrowException()
+    {
+        $this->_router->assemble(null);
+    }
 }