diff --git a/pkgs/development/haskell-modules/configuration-common.nix b/pkgs/development/haskell-modules/configuration-common.nix
index 6da545b0bc181..95ba7d8e4fe8c 100644
--- a/pkgs/development/haskell-modules/configuration-common.nix
+++ b/pkgs/development/haskell-modules/configuration-common.nix
@@ -2228,12 +2228,15 @@ with haskellLib;
 
   # stack-3.7.1 requires Cabal < 3.12
   stack =
+    let
+      stack' = super.stack.overrideScope (self: super: { hpack = self.hpack_0_38_1; });
+    in
     if lib.versionOlder self.ghc.version "9.10" then
-      super.stack
+      stack'
     else
       lib.pipe
         # to reduce rebuilds, don't override Cabal in the entire scope
-        ((super.stack.override { Cabal = self.Cabal_3_10_3_0; }).overrideScope (
+        ((stack'.override { Cabal = self.Cabal_3_10_3_0; }).overrideScope (
           self: super:
           let
             downgradeCabal =
diff --git a/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml b/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml
index 4dfef1e27b2e4..785fddd3c1992 100644
--- a/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml
+++ b/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml
@@ -89,6 +89,7 @@ extra-packages:
   - hasql-pool < 1.1                    # 2025-01-19: Needed for building postgrest
   - hasql-transaction < 1.1.1           # 2025-01-19: Needed for building postgrest
   - hlint == 3.6.*                      # 2025-04-14: needed for hls with ghc-lib-parser 9.6
+  - hpack == 0.38.1                     # 2025-09-18: to match exact version upstream stack-3.7.1 uses
   - hspec-megaparsec == 2.2.0           # 2023-11-18: Latest version compatible with ghc 9.0
   - language-javascript == 0.7.0.0      # required by purescript
   - lsp < 2.5                           # 2024-07-08: need for koka
diff --git a/pkgs/development/haskell-modules/configuration-nix.nix b/pkgs/development/haskell-modules/configuration-nix.nix
index 16573cbe50517..297a7a64a5d1e 100644
--- a/pkgs/development/haskell-modules/configuration-nix.nix
+++ b/pkgs/development/haskell-modules/configuration-nix.nix
@@ -1881,16 +1881,23 @@ builtins.intersectAttrs super {
   extensions = enableSeparateBinOutput super.extensions;
 
   # These test cases access the network
-  hpack = overrideCabal (drv: {
-    testFlags = drv.testFlags or [ ] ++ [
-      "--skip"
-      "/Hpack.Defaults/ensureFile/with 404/does not create any files/"
-      "--skip"
-      "/Hpack.Defaults/ensureFile/downloads file if missing/"
-      "--skip"
-      "/EndToEnd/hpack/defaults/fails if defaults don't exist/"
-    ];
-  }) super.hpack;
+  inherit
+    (lib.mapAttrs (
+      _:
+      overrideCabal (drv: {
+        testFlags = drv.testFlags or [ ] ++ [
+          "--skip"
+          "/Hpack.Defaults/ensureFile/with 404/does not create any files/"
+          "--skip"
+          "/Hpack.Defaults/ensureFile/downloads file if missing/"
+          "--skip"
+          "/EndToEnd/hpack/defaults/fails if defaults don't exist/"
+        ];
+      })
+    ) super)
+    hpack
+    hpack_0_38_1
+    ;
 
   doctest = overrideCabal (drv: {
     testFlags = drv.testFlags or [ ] ++ [
diff --git a/pkgs/development/haskell-modules/hackage-packages.nix b/pkgs/development/haskell-modules/hackage-packages.nix
index 6c207cb876cda..886170a493903 100644
--- a/pkgs/development/haskell-modules/hackage-packages.nix
+++ b/pkgs/development/haskell-modules/hackage-packages.nix
@@ -340852,6 +340852,141 @@ self: {
     }
   ) { };
 
+  hpack_0_38_1 = callPackage (
+    {
+      mkDerivation,
+      aeson,
+      base,
+      bifunctors,
+      bytestring,
+      Cabal,
+      containers,
+      crypton,
+      deepseq,
+      directory,
+      filepath,
+      Glob,
+      hspec,
+      hspec-discover,
+      http-client,
+      http-client-tls,
+      http-types,
+      HUnit,
+      infer-license,
+      interpolate,
+      mockery,
+      mtl,
+      pretty,
+      QuickCheck,
+      scientific,
+      template-haskell,
+      temporary,
+      text,
+      transformers,
+      unordered-containers,
+      vcr,
+      vector,
+      yaml,
+    }:
+    mkDerivation {
+      pname = "hpack";
+      version = "0.38.1";
+      sha256 = "03qygb51jb4r6sg2bkaz7k80h11wgjr27hgpx6h08xm8axdk2gba";
+      revision = "1";
+      editedCabalFile = "0dyd6pp2pk62nynp0x2j9kjddfv43p9inplk4iya7hdldyjs77k0";
+      isLibrary = true;
+      isExecutable = true;
+      libraryHaskellDepends = [
+        aeson
+        base
+        bifunctors
+        bytestring
+        Cabal
+        containers
+        crypton
+        deepseq
+        directory
+        filepath
+        Glob
+        http-client
+        http-client-tls
+        http-types
+        infer-license
+        mtl
+        pretty
+        scientific
+        text
+        transformers
+        unordered-containers
+        vector
+        yaml
+      ];
+      executableHaskellDepends = [
+        aeson
+        base
+        bifunctors
+        bytestring
+        Cabal
+        containers
+        crypton
+        deepseq
+        directory
+        filepath
+        Glob
+        http-client
+        http-client-tls
+        http-types
+        infer-license
+        mtl
+        pretty
+        scientific
+        text
+        transformers
+        unordered-containers
+        vector
+        yaml
+      ];
+      testHaskellDepends = [
+        aeson
+        base
+        bifunctors
+        bytestring
+        Cabal
+        containers
+        crypton
+        deepseq
+        directory
+        filepath
+        Glob
+        hspec
+        http-client
+        http-client-tls
+        http-types
+        HUnit
+        infer-license
+        interpolate
+        mockery
+        mtl
+        pretty
+        QuickCheck
+        scientific
+        template-haskell
+        temporary
+        text
+        transformers
+        unordered-containers
+        vcr
+        vector
+        yaml
+      ];
+      testToolDepends = [ hspec-discover ];
+      description = "A modern format for Haskell packages";
+      license = lib.licenses.mit;
+      hydraPlatforms = lib.platforms.none;
+      mainProgram = "hpack";
+    }
+  ) { };
+
   hpack = callPackage (
     {
       mkDerivation,