diff --git a/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix b/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix
index 6f184c481269..c1beae3e5cc3 100644
--- a/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix
+++ b/pkgs/development/haskell-modules/configuration-ghc-9.10.x.nix
@@ -66,8 +66,7 @@ self: super: {
   # already made the relevant changes.
   # 2025-04-09: jailbreak to allow hedgehog >= 1.5, hspec-hedgehog >=0.2
   extensions = doJailbreak (doDistribute self.extensions_0_1_0_2);
-  # Test suite tightens bound on Diff
-  fourmolu = dontCheck (doDistribute self.fourmolu_0_17_0_0);
+  fourmolu = doDistribute self.fourmolu_0_16_0_0;
   ghc-lib = doDistribute self.ghc-lib_9_10_1_20250103;
   ghc-lib-parser = doDistribute self.ghc-lib-parser_9_10_1_20250103;
   ghc-lib-parser-ex = doDistribute self.ghc-lib-parser-ex_9_10_0_0;
diff --git a/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml b/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml
index 8c2c0bfe0b99..b738fb374ace 100644
--- a/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml
+++ b/pkgs/development/haskell-modules/configuration-hackage2nix/main.yaml
@@ -57,7 +57,7 @@ extra-packages:
   - commonmark-pandoc < 0.2.3           # 2025-04-06: Needed for pandoc 3.6
   - extensions == 0.1.0.2               # 2024-10-20: for GHC 9.10/Cabal 3.12
   - fourmolu == 0.14.0.0                # 2023-11-13: for ghc-lib-parser 9.6 compat
-  - fourmolu == 0.17.0.0                # 2025-01-27: for ghc 9.10 compat
+  - fourmolu == 0.16.0.0                # 2025-01-27: for ghc 9.10 compat
   - fsnotify < 0.4                      # 2024-04-22: required by spago-0.21
   - fuzzyset == 0.2.4                   # 2023-12-20: Needed for building postgrest > 10
   - ghc-api-compat == 8.10.7            # 2022-02-17: preserve for GHC 8.10.7
diff --git a/pkgs/development/haskell-modules/configuration-nix.nix b/pkgs/development/haskell-modules/configuration-nix.nix
index 7ec2f5ceeb20..8dd8bd3e6e41 100644
--- a/pkgs/development/haskell-modules/configuration-nix.nix
+++ b/pkgs/development/haskell-modules/configuration-nix.nix
@@ -1390,7 +1390,7 @@ builtins.intersectAttrs super {
     )
     fourmolu
     fourmolu_0_15_0_0
-    fourmolu_0_17_0_0
+    fourmolu_0_16_0_0
     ;
 
   # Test suite needs to execute 'disco' binary
diff --git a/pkgs/development/haskell-modules/hackage-packages.nix b/pkgs/development/haskell-modules/hackage-packages.nix
index 79f5d4c5438c..3d3fac1f7ab7 100644
--- a/pkgs/development/haskell-modules/hackage-packages.nix
+++ b/pkgs/development/haskell-modules/hackage-packages.nix
@@ -239640,7 +239640,7 @@ self: {
     }
   ) { };
 
-  "fourmolu_0_17_0_0" = callPackage (
+  "fourmolu_0_16_0_0" = callPackage (
     {
       mkDerivation,
       aeson,
@@ -239650,7 +239650,6 @@ self: {
       binary,
       bytestring,
       Cabal-syntax,
-      choice,
       containers,
       deepseq,
       Diff,
@@ -239680,8 +239679,8 @@ self: {
     }:
     mkDerivation {
       pname = "fourmolu";
-      version = "0.17.0.0";
-      sha256 = "1nggip2rf1im4hj0y8py5rakb39wcd5hkq668nq9lj2gvqwqqfhs";
+      version = "0.16.0.0";
+      sha256 = "0vczia3hb1klvbf9fjy32ynyqaka8n7cdk0h8jg6nr89pixla9lc";
       isLibrary = true;
       isExecutable = true;
       libraryHaskellDepends = [
@@ -239692,7 +239691,6 @@ self: {
         binary
         bytestring
         Cabal-syntax
-        choice
         containers
         deepseq
         Diff
@@ -239724,7 +239722,6 @@ self: {
         base
         bytestring
         Cabal-syntax
-        choice
         containers
         Diff
         directory