diff --git a/package.yaml b/package.yaml
index e8c2df4442102f0dfdcb6d30603849f63b4c05cc..d656997f871e419cf9965b63f939614f053fb816 100644
--- a/package.yaml
+++ b/package.yaml
@@ -51,6 +51,7 @@ default-extensions:
 - OverloadedStrings
 - NamedFieldPuns
 - LambdaCase
+- MultiWayIf
 
 ghc-options:
 - -fwarn-unused-do-bind