diff --git a/.changeset/wild-geese-learn.md b/.changeset/wild-geese-learn.md
new file mode 100644
index 0000000..a328e2e
--- /dev/null
+++ b/.changeset/wild-geese-learn.md
@@ -0,0 +1,6 @@
+---
+'@inkathon/contracts': patch
+'@inkathon/frontend': patch
+---
+
+Make cp/copy command work cross-platform (i.e. on Windows) for postinstall and build-all scripts.
diff --git a/contracts/build-all.sh b/contracts/build-all.sh
index f825db1..8c6f0ae 100755
--- a/contracts/build-all.sh
+++ b/contracts/build-all.sh
@@ -4,6 +4,9 @@
 CONTRACTS_DIR="${CONTRACTS_DIR:=./src}" # Base contract directory 
 OUT_DIR="${OUT_DIR:=./deployments}" # Output directory for build files
 
+# Copy command helper (cross-platform)
+CP_CMD=$(command -v cp &> /dev/null && echo "cp" || echo "copy")
+
 # Store all folder names under `CONTRACTS_DIR` in an array
 contracts=()
 for d in $CONTRACTS_DIR/* ; do
@@ -20,7 +23,7 @@ do
 
   echo "Copying build files to '$OUT_DIR/$i/'…"
   mkdir -p $OUT_DIR/$i
-  cp ./target/ink/$i/$i.contract $OUT_DIR/$i/
-  cp ./target/ink/$i/$i.wasm $OUT_DIR/$i/
-  cp ./target/ink/$i/$i.json $OUT_DIR/$i/
+  $CP_CMD ./target/ink/$i/$i.contract $OUT_DIR/$i/
+  $CP_CMD ./target/ink/$i/$i.wasm $OUT_DIR/$i/
+  $CP_CMD ./target/ink/$i/$i.json $OUT_DIR/$i/
 done
\ No newline at end of file
diff --git a/frontend/package.json b/frontend/package.json
index 9d62f44..f3960e3 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -8,7 +8,7 @@
     }
   },
   "scripts": {
-    "postinstall": "cp -n .env.local.example .env.local; true",
+    "postinstall": "[[ ! -e .env.local ]] && CP_CMD=$(command -v cp &> /dev/null && echo \"cp\" || echo \"copy\") && $CP_CMD .env.local.example .env.local; true",
     "dev": "NODE_ENV=development next dev",
     "node": "pnpm run --filter contracts node",
     "dev-and-node": "concurrently \"pnpm dev\" \"pnpm node\" --names \"Next,Node\" --kill-others",