diff --git a/pkgs/development/compilers/ghc/head.nix b/pkgs/development/compilers/ghc/head.nix
index 73808dc431a9..8830b8d179b2 100644
--- a/pkgs/development/compilers/ghc/head.nix
+++ b/pkgs/development/compilers/ghc/head.nix
@@ -1,11 +1,5 @@
 import ./common-hadrian.nix {
-  version = "9.11.20240410";
-  rev = "1b1a92bd25c3f7249cf922c5dbf4415d2de44a36";
-  sha256 = "sha256-2HdhxhVrKn8c/ZOGYoYThqXpod2OPiGXgH+mAV69Ip0=";
-  # The STM benchmark contains chanbench.hs and ChanBench.hs causing a hash
-  # mismatch on case insensitive filesystems. See also
-  # https://gitlab.haskell.org/ghc/packages/stm/-/issues/2
-  postFetch = ''
-    rm -rf "$out/libraries/stm/bench"
-  '';
+  version = "9.11.20240423";
+  rev = "dddc9dff0547733a10e7f505612ab9df3a7c21b6";
+  sha256 = "0993sdmzzyymllck8mcpa1zgrjqjfxcvk1ykvfc18bvbs4145cm9";
 }
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 7db5618ec314..57faad624e40 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -424,8 +424,8 @@ in {
       # https://github.com/xattr/xattr/issues/55 are solved.
       inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
       # 2023-01-15: Support range >= 11 && < 16
-      buildTargetLlvmPackages = pkgsBuildTarget.llvmPackages_15;
-      llvmPackages = pkgs.llvmPackages_15;
+      buildTargetLlvmPackages = pkgsBuildTarget.llvmPackages_18;
+      llvmPackages = pkgs.llvmPackages_18;
     };
 
     ghcjs = compiler.ghcjs810;