diff --git a/package.yaml b/package.yaml
index f261c960de2cb9483b1fee6c3cc92cec63a92f69..bbe7066e8790c9061efcb6f25425e5672540d931 100644
--- a/package.yaml
+++ b/package.yaml
@@ -53,6 +53,7 @@ default-extensions:
 - NamedFieldPuns
 - LambdaCase
 - MultiWayIf
+- ScopedTypeVariables
 
 ghc-options:
 - -fwarn-unused-do-bind