diff --git a/build-constraints.yaml b/build-constraints.yaml
index 79981343..68fd07d5 100644
--- a/build-constraints.yaml
+++ b/build-constraints.yaml
@@ -401,7 +401,7 @@ packages:
         - http-conduit
 
     "Omari Norman <omari@smileystation.com> @massysett":
-        - rainbow
+        - rainbow < 0 # build failure with GHC 8.4 https://github.com/massysett/rainbow/issues/6
         - rainbox < 0 # GHC 8.4 via rainbow
         - multiarg
         - cartel < 0 # GHC 8.4 BuildFailureException Process exited with ExitFailure 1: ./Setup build