diff --git a/pkgs/applications/editors/emacs-modes/melpa-packages.nix b/pkgs/applications/editors/emacs-modes/melpa-packages.nix
index 9574ec43a61..1a647466abd 100644
--- a/pkgs/applications/editors/emacs-modes/melpa-packages.nix
+++ b/pkgs/applications/editors/emacs-modes/melpa-packages.nix
@@ -131,6 +131,7 @@ env NIXPKGS_ALLOW_BROKEN=1 nix-instantiate --show-trace ../../../../ -A emacsPac
 
         irony = super.irony.overrideAttrs (old: {
           cmakeFlags = old.cmakeFlags or [] ++ [ "-DCMAKE_INSTALL_BINDIR=bin" ];
+          NIX_CFLAGS_COMPILE = "-UCLANG_RESOURCE_DIR";
           preConfigure = ''
             cd server
           '';
@@ -144,6 +145,9 @@ env NIXPKGS_ALLOW_BROKEN=1 nix-instantiate --show-trace ../../../../ -A emacsPac
             make check
             cd ../..
           '';
+          preFixup = ''
+            rm -rf $out/share/emacs/site-lisp/elpa/*/server
+          '';
           dontUseCmakeBuildDir = true;
           doCheck = true;
           packageRequires = [ self.emacs ];