diff --git a/composer.json b/composer.json
index 409c710..6cd09cc 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
     ],
     "require": {
         "yiisoft/yii2": "*",
-        "swiftmailer/swiftmailer": "*"
+        "swiftmailer/swiftmailer": "~5.4"
     },
     "autoload": {
         "psr-4": { "yii\\swiftmailer\\": "" }