diff --git a/build-constraints.yaml b/build-constraints.yaml
index 19820e84..eba63c1d 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -2963,6 +2963,9 @@ skipped-benchmarks:
     # https://github.com/athanclark/rose-trees/pull/5
     - rose-trees
 
+    # https://github.com/int-index/union/issues/4
+    - union
+
 # end of skipped-benchmarks