diff --git a/build-constraints.yaml b/build-constraints.yaml
index 6ab8df7f..4bd4b56b 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -7849,6 +7849,8 @@ expected-benchmark-failures:
 # Haddocks which are expected to fail. Same concept as expected test failures.
 expected-haddock-failures:
 
+    # Compilation with GHC 9.0.1 crashes with Prelude.chr: bad argument
+
     # Requires build before haddock, which doesn't always happen in incremental
     # builds. Could consider special-casing this requirement.
     - gtk3