diff --git a/pkgs/development/haskell-modules/configuration-nix.nix b/pkgs/development/haskell-modules/configuration-nix.nix
index 91e95de94af5..1051c4e416f1 100644
--- a/pkgs/development/haskell-modules/configuration-nix.nix
+++ b/pkgs/development/haskell-modules/configuration-nix.nix
@@ -501,4 +501,6 @@ self: super: builtins.intersectAttrs super {
   # Without this override, the builds lacks pkg-config.
   opencv-extra = addPkgconfigDepend super.opencv-extra (pkgs.opencv3.override { enableContrib = true; });
 
+  # Written against the 6.X series of megaparsec
+  htoml-megaparsec = super.htoml-megaparsec.override { megaparsec = self.megaparsec_6_2_0; };
 }