diff --git a/extensions/subscriptions/composer.json b/extensions/subscriptions/composer.json
index 2f619beea..d6075c3d4 100644
--- a/extensions/subscriptions/composer.json
+++ b/extensions/subscriptions/composer.json
@@ -19,7 +19,7 @@
         }
     ],
     "require": {
-        "flarum/core": "^1.6"
+        "flarum/core": "^1.6.3"
     },
     "autoload": {
         "psr-4": {