diff --git a/build-constraints.yaml b/build-constraints.yaml
index 0e8d3b75..de242a47 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -9410,6 +9410,7 @@ expected-test-failures:
     - tar-conduit # https://github.com/snoyberg/tar-conduit/issues/33
     - markov-chain-usage-model # https://github.com/advancedtelematic/markov-chain-usage-model/issues/44
     - unicode-data # 0.4.0.1
+    - sydtest # 0.15.1.1
 
     # Intermittent failures or unreliable. These tests may pass when
     # re-enabled, but will eventually fail again.