diff --git a/pkgs/applications/editors/emacs/elisp-packages/manual-packages/llvm-mode/default.nix b/pkgs/applications/editors/emacs/elisp-packages/manual-packages/llvm-mode/default.nix
index 02fec5ef7f72..4938f2d98be1 100644
--- a/pkgs/applications/editors/emacs/elisp-packages/manual-packages/llvm-mode/default.nix
+++ b/pkgs/applications/editors/emacs/elisp-packages/manual-packages/llvm-mode/default.nix
@@ -1,14 +1,10 @@
-{ trivialBuild
-, llvmPackages
-}:
+{ melpaBuild, llvmPackages }:
 
-trivialBuild {
+melpaBuild {
   pname = "llvm-mode";
-  inherit (llvmPackages.llvm) src version;
+  inherit (llvmPackages.llvm) version;
 
-  postUnpack = ''
-    sourceRoot="$sourceRoot/llvm/utils/emacs"
-  '';
+  src = "${llvmPackages.llvm.src}/llvm/utils/emacs";
 
   meta = {
     inherit (llvmPackages.llvm.meta) homepage license;