diff --git a/build-constraints.yaml b/build-constraints.yaml
index 170bb16f..25507cfa 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -6779,6 +6779,9 @@ packages:
       # https://github.com/commercialhaskell/stackage/issues/6278
       - ad < 4.5
 
+      # https://github.com/commercialhaskell/stackage/issues/6288
+      - mmark-ext < 0.2.1.4
+
 # end of packages
 
 # Package flags are applied to individual packages, and override the values of