diff --git a/pkgs/development/haskell-modules/hackage-packages.nix b/pkgs/development/haskell-modules/hackage-packages.nix
index d1a08377698e..45839074b79b 100644
--- a/pkgs/development/haskell-modules/hackage-packages.nix
+++ b/pkgs/development/haskell-modules/hackage-packages.nix
@@ -62996,20 +62996,21 @@ self: {
        license = stdenv.lib.licenses.mit;
      }) {};
 
-  "flat-mcmc_1_1_1" = callPackage
-    ({ mkDerivation, base, mcmc-types, monad-par, monad-par-extras
-     , mwc-probability, pipes, primitive, transformers, vector
+  "flat-mcmc_1_2_2" = callPackage
+    ({ mkDerivation, base, formatting, mcmc-types, monad-par
+     , monad-par-extras, mwc-probability, pipes, primitive, text
+     , transformers, vector
      }:
      mkDerivation {
        pname = "flat-mcmc";
-       version = "1.1.1";
-       sha256 = "24e2bc1b4728dd54326908332322f227cc2bf3548e6e1b07f0695a1c3167a88c";
+       version = "1.2.2";
+       sha256 = "c70914ac35058f847e5faf173076403b8feb7bb8c8c96c34ba728aca031f6937";
        libraryHaskellDepends = [
-         base mcmc-types monad-par monad-par-extras mwc-probability pipes
-         primitive transformers vector
+         base formatting mcmc-types monad-par monad-par-extras
+         mwc-probability pipes primitive text transformers vector
        ];
        testHaskellDepends = [ base vector ];
-       homepage = "http://jtobin.github.com/flat-mcmc";
+       homepage = "https://github.com/jtobin/flat-mcmc";
        description = "Painless general-purpose sampling";
        license = stdenv.lib.licenses.mit;
        hydraPlatforms = stdenv.lib.platforms.none;