diff --git a/build-constraints.yaml b/build-constraints.yaml
index e872b52a..5024c56b 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2647,7 +2647,7 @@ packages:
         - irc-client
 
     "Rudy Matela <rudy@matela.com.br> @rudymatela":
-        - leancheck
+        - leancheck < 1.0.0              # https://github.com/commercialhaskell/stackage/issues/6693
         - leancheck-instances
         - fitspec
         - express