diff --git a/build-constraints.yaml b/build-constraints.yaml
index b6143091..790dfe1d 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2447,7 +2447,7 @@ packages:
         # parser-combinators-tests # https://github.com/commercialhaskell/stackage/issues/4540
         - path
         - path-io
-        - req
+        - req < 2.1.0 # https://github.com/commercialhaskell/stackage/issues/4677
         - req-conduit
         - stache
         - tagged-identity