diff --git a/pkgs/by-name/ev/evcxr/package.nix b/pkgs/by-name/ev/evcxr/package.nix
index fb6528a60c9e..7df91febe656 100644
--- a/pkgs/by-name/ev/evcxr/package.nix
+++ b/pkgs/by-name/ev/evcxr/package.nix
@@ -30,7 +30,7 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   cargoHash = "sha256-HJrEXt6O7qCNJ/xOh4kjmqKJ22EVwBTzV1S+q98k0VQ=";
 
-  RUST_SRC_PATH = "${rustPlatform.rustLibSrc}";
+  env.RUST_SRC_PATH = "${rustPlatform.rustLibSrc}";
 
   nativeBuildInputs = [
     pkg-config