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 18fc916a2b1d..9d4b632edba9 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-8.4.x.nix
@@ -788,4 +788,11 @@ self: super: {
     jailbreak       = true;
   });
 
+  # Fix missing semigroup instance for Journal.
+  hledger-lib = appendPatch super.hledger-lib (pkgs.fetchpatch
+    { url = https://github.com/simonmichael/hledger/pull/718.patch;
+      sha256 = "1gcs9j934wvk9hbn27zm42dnvf4x1gxr54li4kdw3zi3160y2l5c";
+      stripLen = 1;
+    });
+
 }