diff --git a/build-constraints.yaml b/build-constraints.yaml
index 63ce00df..797c02de 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -3885,6 +3885,9 @@ packages:
         # https://github.com/commercialhaskell/stackage/issues/4196
         - tasty < 1.2
 
+        # https://github.com/commercialhaskell/stackage/issues/4214
+        - haskell-src-exts < 1.21
+
 # end of packages
 
 # Package flags are applied to individual packages, and override the values of