diff --git a/build-constraints.yaml b/build-constraints.yaml
index 74170888..e7022178 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -8088,6 +8088,7 @@ expected-test-failures:
     - spatial-math
     - streamly-bytestring # 0.1.4
     - subcategories
+    - sydtest # https://github.com/commercialhaskell/stackage/issues/6729
     - tasty-fail-fast
     - triplesec
     - turtle