diff --git a/build-constraints.yaml b/build-constraints.yaml
index 8114de6f..abc970f1 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -4701,7 +4701,7 @@ packages:
         - special-values
         - splice
         - split
-        - splitmix
+        - splitmix < 0.1  # Broken due to upper bound on QuickCheck, #5566
         - sql-words
         - stateref
         - statistics