diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 421bba24568..5842cc3331f 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -282,6 +282,9 @@ rec {
     lts-3_11 = packages.ghc7102.override {
       packageSetConfig = callPackage ../development/haskell-modules/configuration-lts-3.11.nix { };
     };
+    lts-3_12 = packages.ghc7102.override {
+      packageSetConfig = callPackage ../development/haskell-modules/configuration-lts-3.12.nix { };
+    };
 
   };
 }