diff --git a/build-constraints.yaml b/build-constraints.yaml
index a1326d81..d10b552d 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -1664,7 +1664,7 @@ packages:
         - th-lego
         - vector-builder
         - vector-extras
-        - yaml-unscrambler
+        - yaml-unscrambler < 0 # https://github.com/commercialhaskell/stackage/issues/6888 - does not compile with selective-0.6.
         - xml-parser
 
     "Iustin Pop <iustin@k1024.org> @iustin":