diff --git a/c2rust-ast-exporter/build.rs b/c2rust-ast-exporter/build.rs
index 39743b083b..9403e50d01 100644
--- a/c2rust-ast-exporter/build.rs
+++ b/c2rust-ast-exporter/build.rs
@@ -127,8 +127,16 @@ fn build_native(llvm_info: &LLVMInfo) {
             // Build libclangAstExporter.a with cmake
             let dst = Config::new("src")
                 // Where to find LLVM/Clang CMake files
-                .define("LLVM_DIR", &format!("{}/cmake/llvm", llvm_lib_dir))
-                .define("Clang_DIR", &format!("{}/cmake/clang", llvm_lib_dir))
+                .define(
+                    "LLVM_DIR",
+                    &env::var("CMAKE_LLVM_DIR")
+                        .unwrap_or_else(|_| format!("{}/cmake/llvm", llvm_lib_dir)),
+                )
+                .define(
+                    "Clang_DIR",
+                    &env::var("CMAKE_CLANG_DIR")
+                        .unwrap_or_else(|_| format!("{}/cmake/clang", llvm_lib_dir)),
+                )
                 // What to build
                 .build_target("clangAstExporter")
                 .build();
diff --git a/shell.nix b/default.nix
similarity index 53%
rename from shell.nix
rename to default.nix
index 4b52603e75..cf6bbada8e 100644
--- a/shell.nix
+++ b/default.nix
@@ -1,5 +1,5 @@
 let
-  nixpkgs = import <nixpkgs> {};
+  nixpkgs = import <nixpkgs> { };
   inherit (nixpkgs) pkgs llvmPackages;
   stdenv = pkgs.clangStdenv;
 in
@@ -9,11 +9,14 @@ stdenv.mkDerivation {
     pkgs.clang
     pkgs.cmake
     pkgs.llvm
+    pkgs.libllvm
     pkgs.openssl
     pkgs.pkgconfig
     pkgs.python3
     pkgs.rustup
     pkgs.zlib
   ];
-  LIBCLANG_PATH="${llvmPackages.libclang}/lib";
+  LIBCLANG_PATH = "${pkgs.libclang.lib}/lib";
+  CMAKE_LLVM_DIR = "${llvmPackages.libllvm.dev}/lib/cmake/llvm";
+  CMAKE_CLANG_DIR = "${llvmPackages.libclang.dev}/lib/cmake/clang";
 }