diff --git a/build-constraints.yaml b/build-constraints.yaml
index c2e644a6..8efa29cf 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -707,6 +707,7 @@ packages:
 
         # Force a specific version that's compatible with transformers 0.3
         - transformers-compat == 0.3.3.3
+        - mtl-compat < 0.2 # https://github.com/fpco/stackage/issues/446
 
         # https://github.com/fpco/stackage/issues/291
         - random < 1.0.1.3