diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 7a5a2bfccc7..1125b8b9d9f 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -412,7 +412,10 @@ rec {
     lts-6_2 = packages.ghc7103.override {
       packageSetConfig = callPackage ../development/haskell-modules/configuration-lts-6.2.nix { };
     };
-    lts-6 = packages.lts-6_2;
+    lts-6_3 = packages.ghc7103.override {
+      packageSetConfig = callPackage ../development/haskell-modules/configuration-lts-6.3.nix { };
+    };
+    lts-6 = packages.lts-6_3;
 
     lts = packages.lts-6;
   };