diff --git a/build-constraints.yaml b/build-constraints.yaml
index daf3df30..50884012 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -4902,6 +4902,9 @@ packages:
       # https://github.com/commercialhaskell/stackage/issues/4992
       - swagger2 < 2.5
 
+      # https://github.com/commercialhaskell/stackage/issues/4994
+      - rainbow < 0.34.1
+
 # end of packages
 
 # Package flags are applied to individual packages, and override the values of