diff --git a/pkgs/development/tools/haskell/vaultenv/default.nix b/pkgs/development/tools/haskell/vaultenv/default.nix
index 6c339bf31b5..419f4530dca 100644
--- a/pkgs/development/tools/haskell/vaultenv/default.nix
+++ b/pkgs/development/tools/haskell/vaultenv/default.nix
@@ -15,6 +15,11 @@ mkDerivation rec {
 
   buildTools = [ hpack ];
 
+  prePatch = ''
+    substituteInPlace package.yaml \
+        --replace -Werror ""
+  '';
+
   isLibrary = false;
   isExecutable = true;
   executableHaskellDepends = [