diff --git a/build-constraints.yaml b/build-constraints.yaml
index cf00358e..4f959d9e 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -6800,6 +6800,9 @@ packages:
 
       # https://github.com/commercialhaskell/stack/issues/5670 (fails with Cabal-3.4)
       - stack < 0
+
+      # https://github.com/commercialhaskell/stackage/issues/6401
+      - rope-utf16-splay < 0.4
 # end of packages
 
 # Package flags are applied to individual packages, and override the values of