diff --git a/src/Symfony/Bundle/FrameworkBundle/Routing/Router.php b/src/Symfony/Bundle/FrameworkBundle/Routing/Router.php
index 8d50592af0..016189110e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Routing/Router.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Routing/Router.php
@@ -94,7 +94,7 @@ class Router extends BaseRouter implements WarmableInterface
                 foreach ($route->getRequirements() as $name => $value) {
                      $route->setRequirement($name, $this->resolveString($value));
                 }
-
+                $collection->setPrefix('/'.ltrim($this->resolveString($collection->getPrefix()), '/'));
                 $route->setPattern($this->resolveString($route->getPattern()));
             }
         }
diff --git a/src/Symfony/Component/Routing/RouteCollection.php b/src/Symfony/Component/Routing/RouteCollection.php
index 596a8bf897..9917384d3d 100644
--- a/src/Symfony/Component/Routing/RouteCollection.php
+++ b/src/Symfony/Component/Routing/RouteCollection.php
@@ -259,6 +259,16 @@ class RouteCollection implements \IteratorAggregate, \Countable
         return $this->prefix;
     }
 
+    /**
+     * Sets the prefix (used to resolve placeholders).
+     *
+     * @param string The prefix
+     */
+    public function setPrefix($prefix)
+    {
+        $this->prefix = $prefix;
+    }
+
     /**
      * Returns an array of resources loaded to build this collection.
      *