diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 1706beda3156d229a453415d26d8119ba6487a38..0211783ab95083ffba0bec80de1a4956f702fdbb 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -7,7 +7,6 @@ variables:
     DEFAULT: "master"
     OCAML: "4_08"
     FRAMA_CI_OPT: "--override frama-clang:$CI_COMMIT_REF_NAME,$CI_COMMIT_SHA"
-    NIXPKGS_ALLOW_UNFREE: "1"
 
 #avoid a nix error https://github.com/NixOS/nix/issues/2087
 git-update:
diff --git a/nix/default.nix b/nix/default.nix
index 456cddc574c93ba0ab993fbf0b60c78ddb70fe34..8f882bd297bb195263019f584e91bb4954aaa4da 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -16,7 +16,6 @@ plugins.helpers.simple_plugin
      name = "frama-clang";
      deps = [ unstablePckgs.llvmPackages_9.clang-unwrapped unstablePckgs.llvm_9 pkgs.gnused ];
      opamPackages = [ "camlp5" { name = "alt-ergo"; constraint = "=2.0.0"; } ];
-     configure_options = "-with-clang-includedir=${unstablePckgs.llvmPackages_9.clang-unwrapped}";
      preFramaCTests = ''
        echo CONFIGURING Why3 for Frama_Clang.
        export HOME=$(mktemp -d)