diff --git a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
index 76f9348e1deab..b69bd6d3bdd32 100644
--- a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
+++ b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
@@ -111,11 +111,13 @@ public function getEnv($prefix, $name, \Closure $getEnv)
         }
 
         if ('const' === $prefix) {
+            $env = \str_replace("\\\\","\\", $env);
+            
             if (!defined($env)) {
                 throw new RuntimeException(sprintf('Env var "%s" maps to undefined constant "%s".', $name, $env));
             }
 
-            return constant($name);
+            return constant($env);
         }
 
         if ('base64' === $prefix) {