diff --git a/pkgs/development/compilers/ghc/common-hadrian.nix b/pkgs/development/compilers/ghc/common-hadrian.nix
index 33f95c9c37eb..d9635b7cfcd2 100644
--- a/pkgs/development/compilers/ghc/common-hadrian.nix
+++ b/pkgs/development/compilers/ghc/common-hadrian.nix
@@ -323,6 +323,19 @@
       # Fix docs build with Sphinx >= 9 https://gitlab.haskell.org/ghc/ghc/-/issues/26810
       ++ [ ./ghc-9.6-or-later-docs-sphinx-9.patch ]
 
+      # Fixes rts/Types.h missing from the install when targeting javascript
+      # See https://gitlab.haskell.org/ghc/ghc/-/merge_requests/15740, krank:ignore-line
+      # https://gitlab.haskell.org/ghc/ghc/-/issues/27033. krank:ignore-line
+      # TODO(@sternenseemann): patch likely included in 9.12.4
+      ++ lib.optionals (lib.versionAtLeast version "9.12.3" && lib.versionOlder version "9.15") [
+        (fetchpatch {
+          name = "ghc-9.12.3-ghcjs-install-rts-types.h.patch";
+          url = "https://gitlab.haskell.org/ghc/ghc/-/commit/5b1be555be4f0989d78c274991c5046d7ac6d25e.patch";
+          hash = "sha256-pv4NDyQ6FlZgmTYZ4Ghis4qggt7nCDMhqGaFxTxVPac=";
+          includes = [ "rts/rts.cabal" ];
+        })
+      ]
+
       ++ (import ./common-llvm-patches.nix { inherit lib version fetchpatch; });
 
     stdenv = stdenvNoCC;
diff --git a/pkgs/development/compilers/ghc/head.nix b/pkgs/development/compilers/ghc/head.nix
index e343cd33cef8..b745931a6ca9 100644
--- a/pkgs/development/compilers/ghc/head.nix
+++ b/pkgs/development/compilers/ghc/head.nix
@@ -1,5 +1,5 @@
 import ./common-hadrian.nix {
-  version = "9.15.20251225";
-  rev = "a3afae0c85fa57479378a5df5bbde2e3a8da8a06";
-  sha256 = "sha256-inZFFKnCb8C7RTlKP2bnHOLfc1GveGi6Wy0uAaLv1Kk=";
+  version = "9.15.20260322";
+  rev = "44f118f09dcde49f64d03e427312df4732f2d4a4";
+  sha256 = "sha256-xby7HKyK5P1Y5DjKbVe62piDCY4Ujb4pbv8AJ7sQ0HI=";
 }