diff --git a/build-constraints.yaml b/build-constraints.yaml
index c34d3f74..c5039481 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -5254,8 +5254,8 @@ packages:
         - lsql-csv
 
     "Sebastian Graf <sgraf1337@gmail.com> @sgraf812":
-        - happy-lib
-        - happy
+        - happy-lib < 2.1 # latest 2.1 is marked deprecated
+        - happy < 2.1 # latest 2.1 is marked deprecated
 
     "Max Ulidtko <ulidtko@gmail.com> @ulidtko":
         - cabal-doctest