diff --git a/pkgs/development/haskell-modules/configuration-ghc-8.8.x.nix b/pkgs/development/haskell-modules/configuration-ghc-8.8.x.nix
index b9e3d988a2c..5f236f77685 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-8.8.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-8.8.x.nix
@@ -165,5 +165,9 @@ self: super: {
     url = "https://raw.githubusercontent.com/hvr/head.hackage/master/patches/aeson-1.4.3.0.patch";
     sha256 = "1z6wmsmc682qs3y768r0zx493dxardwbsp0wdc4dsx83c0m5x66f";
   });
+  cassava = appendPatch super.cassava (pkgs.fetchpatch {
+    url = "https://raw.githubusercontent.com/hvr/head.hackage/master/patches/cassava-0.5.1.0.patch";
+    sha256 = "11scwwjp94si90vb8v5yr291g9qwv5l223z8y0g0lc63932bp63g";
+  });
 
 }