diff --git a/build-constraints.yaml b/build-constraints.yaml
index add96dad..4eaa15d4 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -9,6 +9,7 @@ cabal-format-version: "2.0"
 packages:
     "Matthew Ahrens <matt.p.ahrens@gmail.com> @mpahrens":
         - forkable-monad
+        - butter
     "Iris Ward <aditu.venyhandottir@gmail.com> @AdituV":
         - typenums