diff --git a/build-constraints.yaml b/build-constraints.yaml
index 662226b4..9edcc208 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2870,6 +2870,7 @@ packages:
         - bson
 
     "Alexis King <lexi.lambda@gmail.com> @lexi-lambda":
+        - monad-mock
         - test-fixture
         - text-conversions
         - th-to-exp