diff --git a/build-constraints.yaml b/build-constraints.yaml
index 711459c2..42bb5382 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -8049,6 +8049,7 @@ expected-test-failures:
     - hspec-junit-formatter # https://github.com/freckle/hspec-junit-formatter/issues/14
     - persistent # https://github.com/commercialhaskell/stackage/issues/6037
     - reanimate-svg # https://github.com/commercialhaskell/stackage/issues/5688
+    - wai-saml2 # https://github.com/mbg/wai-saml2/issues/15
 
     # Testcase assertion failures, or other runtime failures.
     # These can be real testsuite bugs, or maybe limitations in test cases or the test setup.