diff --git a/README.md b/README.md
index 2034675..22a3708 100644
--- a/README.md
+++ b/README.md
@@ -252,9 +252,9 @@ The library is organized in layers:
 
 The flasher includes pre-compiled bootloader stubs from [esp-flasher-stub](https://github.com/espressif/esp-flasher-stub) releases. To update stubs:
 
-1. Edit `STUB_VERSION` in `tools/update-stubs.sh` to the desired release version
+1. Edit `stubVersion` in `tools/update-stubs.go` to the desired release version
 2. Run `go generate ./pkg/espflasher/...` to download and embed the latest stubs
-3. The `go:generate` directive in `pkg/espflasher/stub.go` will invoke `tools/update-stubs.sh`
+3. The `go:generate` directive in `pkg/espflasher/stub.go` will invoke `tools/update-stubs.go`
 
 ## Protocol Reference
 
diff --git a/pkg/espflasher/stub.go b/pkg/espflasher/stub.go
index d3df9e2..d8f0901 100644
--- a/pkg/espflasher/stub.go
+++ b/pkg/espflasher/stub.go
@@ -7,7 +7,7 @@ import (
 	"fmt"
 )
 
-//go:generate bash ../../tools/update-stubs.sh
+//go:generate go run ../../tools/update-stubs.go
 //go:embed stubs
 var stubFS embed.FS
 
diff --git a/tools/update-stubs.go b/tools/update-stubs.go
new file mode 100644
index 0000000..ccde755
--- /dev/null
+++ b/tools/update-stubs.go
@@ -0,0 +1,71 @@
+// Command update-stubs downloads pre-compiled bootloader stubs from the
+// esp-flasher-stub GitHub releases and writes them to pkg/espflasher/stubs/.
+package main
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+)
+
+const (
+	stubVersion = "v0.5.1"
+	baseURL     = "https://github.com/espressif/esp-flasher-stub/releases/download/" + stubVersion
+)
+
+var chips = []string{
+	"esp8266",
+	"esp32",
+	"esp32s2",
+	"esp32s3",
+	"esp32c2",
+	"esp32c3",
+	"esp32c5",
+	"esp32c6",
+	"esp32h2",
+}
+
+func main() {
+	// Resolve the stubs directory relative to this tool's source file.
+	stubDir := filepath.Join("..", "pkg", "espflasher", "stubs")
+	if dir := os.Getenv("STUB_DIR"); dir != "" {
+		stubDir = dir
+	}
+
+	fmt.Printf("Downloading stubs from %s to %s\n", baseURL, stubDir)
+
+	for _, chip := range chips {
+		url := baseURL + "/" + chip + ".json"
+		dest := filepath.Join(stubDir, chip+".json")
+
+		if err := download(url, dest); err != nil {
+			fmt.Fprintf(os.Stderr, "error downloading %s: %v\n", chip, err)
+			os.Exit(1)
+		}
+	}
+
+	fmt.Printf("Successfully updated all %d stubs to %s\n", len(chips), stubVersion)
+}
+
+func download(url, dest string) error {
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("HTTP %s for %s", resp.Status, url)
+	}
+
+	f, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = io.Copy(f, resp.Body)
+	return err
+}
diff --git a/tools/update-stubs.sh b/tools/update-stubs.sh
deleted file mode 100755
index edfa41d..0000000
--- a/tools/update-stubs.sh
+++ /dev/null
@@ -1,15 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-STUB_VERSION=v0.5.1
-CHIPS=(esp8266 esp32 esp32s2 esp32s3 esp32c2 esp32c3 esp32c5 esp32c6 esp32h2)
-BASE_URL=https://github.com/espressif/esp-flasher-stub/releases/download/${STUB_VERSION}
-STUB_DIR=$(cd "$(dirname "$0")/.." && pwd)/pkg/espflasher/stubs
-
-echo "Downloading stubs from ${BASE_URL} to ${STUB_DIR}"
-
-for chip in "${CHIPS[@]}"; do
-  curl -sL -o "${STUB_DIR}/${chip}.json" "${BASE_URL}/${chip}.json"
-done
-
-echo "Successfully updated all ${#CHIPS[@]} stubs to ${STUB_VERSION}"