diff --git a/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix b/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
index 9d4b632edba..d216e8a41a0 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
@@ -795,4 +795,7 @@ self: super: {
       stripLen = 1;
     });
 
+  # Old versions don't compile.
+  vty = self.vty_5_20;
+
 }