diff --git a/pkgs/development/compilers/ghc/head.nix b/pkgs/development/compilers/ghc/head.nix
index d6af1a4f1576..74e03550255a 100644
--- a/pkgs/development/compilers/ghc/head.nix
+++ b/pkgs/development/compilers/ghc/head.nix
@@ -38,7 +38,7 @@
 , # Whether to build terminfo.
   enableTerminfo ? !stdenv.targetPlatform.isWindows
 
-, version ? "8.11.20200824"
+, version ? "9.3.20210504"
 , # What flavour to build. An empty string indicates no
   # specific flavour and falls back to ghc default values.
   ghcFlavour ? lib.optionalString (stdenv.targetPlatform != stdenv.hostPlatform)
@@ -110,8 +110,8 @@ stdenv.mkDerivation (rec {
 
   src = fetchgit {
     url = "https://gitlab.haskell.org/ghc/ghc.git/";
-    rev = "3f50154591ada9064351ccec4adfe6df53ca2439";
-    sha256 = "1w2p5bc74aswspzvgvrhcb95hvj5ky38rgqqjvrri19z2qyiky6d";
+    rev = "049c3a83fbce67e58e70c727d89e8331608a4e04";
+    sha256 = "0dk7c9ywam9fj33lqzpwxhiwz017m58j6ixvc8b07kzp7kskaxq7";
   };
 
   enableParallelBuilding = true;
@@ -139,6 +139,9 @@ stdenv.mkDerivation (rec {
     export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
     export STRIP="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}strip"
 
+    # otherwise haddock fails when generating the compiler docs
+    export LANG=C.UTF-8
+
     echo -n "${buildMK dontStrip}" > mk/build.mk
     echo ${version} > VERSION
     echo ${src.rev} > GIT_COMMIT_ID
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 571fe6773006..af4125d67131 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -86,7 +86,7 @@ in {
       llvmPackages = pkgs.llvmPackages_10;
     };
     ghcHEAD = callPackage ../development/compilers/ghc/head.nix {
-      bootPkgs = packages.ghc884; # no binary yet
+      bootPkgs = packages.ghc8104; # no binary yet
       inherit (buildPackages.python3Packages) sphinx;
       buildLlvmPackages = buildPackages.llvmPackages_10;
       llvmPackages = pkgs.llvmPackages_10;