diff --git a/web/web-shell/script.js b/web/web-shell/script.js
index 53093d3..c9a67d5 100644
--- a/web/web-shell/script.js
+++ b/web/web-shell/script.js
@@ -1,4 +1,32 @@
-//import {Mutex} from "./mutex.js"
+class Mutex {
+    constructor() {
+        this._queue = [] // Queue of pending tasks
+        this._locked = false // Mutex state
+    }
+
+    lock() {
+        if (this._locked) {
+            // If locked, return a promise that resolves when the mutex is unlocked
+            return new Promise((resolve) => this._queue.push(resolve))
+        } else {
+            // If not locked, set it to locked and return a resolved promise
+            this._locked = true
+            return Promise.resolve()
+        }
+    }
+
+    unlock() {
+        if (this._queue.length > 0) {
+            // If there are tasks waiting in the queue, pop the first task and resolve its promise
+            const nextTask = this._queue.shift()
+            nextTask()
+        } else {
+            // If no tasks in the queue, just unlock the mutex
+            this._locked = false
+        }
+    }
+}
+const mutex = new Mutex()
 
 var emulator
 
@@ -16,29 +44,35 @@ window["testy"] = testy
 
 // Run a command via the serial port (/dev/ttyS0) and return the output.
 function run(cmd) {
-    emulator.serial0_send(cmd + "\n")
-
     return new Promise((resolve, reject) => {
-        var output = ""
-        var listener = (char) => {
-            if (char !== "\r") {
-                output += char
-            }
+        mutex.lock().then(() => {
+            emulator.serial0_send(cmd + "\n")
 
-            if (output.endsWith("# ")) {
-                emulator.remove_listener("serial0-output-char", listener)
-                let outputWithoutPrompt = output.slice(0, -4)
-                let outputWithoutFirstLine = outputWithoutPrompt.slice(
-                    outputWithoutPrompt.indexOf("\n") + 1
-                )
-                if (outputWithoutFirstLine.endsWith("\n")) {
-                    outputWithoutFirstLine = outputWithoutFirstLine.slice(0, -1)
+            var output = ""
+            var listener = (char) => {
+                if (char !== "\r") {
+                    output += char
+                }
+
+                if (output.endsWith("# ")) {
+                    emulator.remove_listener("serial0-output-char", listener)
+                    let outputWithoutPrompt = output.slice(0, -4)
+                    let outputWithoutFirstLine = outputWithoutPrompt.slice(
+                        outputWithoutPrompt.indexOf("\n") + 1
+                    )
+                    if (outputWithoutFirstLine.endsWith("\n")) {
+                        outputWithoutFirstLine = outputWithoutFirstLine.slice(
+                            0,
+                            -1
+                        )
+                    }
+                    emulator.remove_listener("serial0-output-char", listener)
+                    mutex.unlock()
+                    resolve(outputWithoutFirstLine)
                 }
-                emulator.remove_listener("serial0-output-char", listener)
-                resolve(outputWithoutFirstLine)
             }
-        }
-        emulator.add_listener("serial0-output-char", listener)
+            emulator.add_listener("serial0-output-char", listener)
+        })
     })
 }
 window["run"] = run