diff --git a/rust/gbt/package.json b/rust/gbt/package.json
index 970ae18bf..77ca25da6 100644
--- a/rust/gbt/package.json
+++ b/rust/gbt/package.json
@@ -11,7 +11,7 @@
     "build-release": "npm run build -- --release --strip",
     "check-cargo-version": "VER=$(cat rust-toolchain) ; if ! cargo version | grep \"cargo $VER\" >/dev/null ; then echo -e \"\\033[1;35m[[[[WARNING]]]]: cargo version mismatch with ./rust-toolchain version ($VER)!!!\\033[0m\" >&2; fi",
     "clean": "rm -rf ./target/ ./node_modules/ *.node package-lock.json",
-    "to-backend": "rm -rf ../../backend/rust-gbt && mkdir ../../backend/rust-gbt && cp index.js index.d.ts package.json *.node ../../backend/rust-gbt",
+    "to-backend": "FD=${FD:-../../backend/rust-gbt/} ; rm -rf $FD && mkdir $FD && cp index.js index.d.ts package.json *.node $FD",
     "prepublishOnly": "napi prepublish -t npm",
     "test": "cargo test"
   },