diff --git a/build-constraints.yaml b/build-constraints.yaml
index 5a831f6d..81118969 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -3614,6 +3614,7 @@ packages:
         - versions < 0 # GHC 8.4 via base-4.11.0.0
         - wavefront < 0 # GHC 8.4 via base-4.11.0.0
         - apply-refact < 0 # GHC 8.4 via ghc-8.4.1
+        - brittany < 0 # GHC 8.4 via ghc-8.4.1
         - ghc-parser < 0 # GHC 8.4 via ghc-8.4.1
         - haskell-tools-prettyprint < 0 # GHC 8.4 via ghc-8.4.1
         - haskell-tools-rewrite < 0 # GHC 8.4 via ghc-8.4.1