diff --git a/src/I18n/TranslatorRegistry.php b/src/I18n/TranslatorRegistry.php
index <HASH>..<HASH> 100644
--- a/src/I18n/TranslatorRegistry.php
+++ b/src/I18n/TranslatorRegistry.php
@@ -145,7 +145,9 @@ class TranslatorRegistry extends TranslatorLocator
             return $this->registry[$name][$locale] = $this->_getTranslator($name, $locale);
         }
 
-        $key = "translations.$name.$locale";
+        // Cache keys cannot contain / if they go to file engine.
+        $keyName = str_replace('/', '.', $name);
+        $key = "translations.{$keyName}.{$locale}";
         $translator = $this->_cacher->get($key);
         if (!$translator || !$translator->getPackage()) {
             $translator = $this->_getTranslator($name, $locale);
Fix invalid key in TranslatorRegistry.