diff --git a/pyxtermjs/app.py b/pyxtermjs/app.py
index 2d66f4f..19c65a7 100644
--- a/pyxtermjs/app.py
+++ b/pyxtermjs/app.py
@@ -50,7 +50,7 @@ def pty_input(data):
     """
     if app.config["fd"]:
         # print("writing to ptd: %s" % data["input"])
-        os.write(app.config["fd"], data["input"].encode())
+        os.write(app.config["fd"], data["input"]["key"].encode())
 
 
 @socketio.on("resize", namespace="/pty")
diff --git a/pyxtermjs/index.html b/pyxtermjs/index.html
index b901d69..36bea3a 100644
--- a/pyxtermjs/index.html
+++ b/pyxtermjs/index.html
@@ -7,7 +7,7 @@
     font-family: arial;
   }
   </style>
-  <link rel="stylesheet" href="https://unpkg.com/xterm@3.6.0/dist/xterm.css" />
+  <link rel="stylesheet" href="https://unpkg.com/xterm@4.11.0/css/xterm.css" />
 </head>
 <body>
 
@@ -20,31 +20,32 @@
   built by <a href="https://grassfedcode.com">Chad Smith</a> <a href="https://github.com/cs01">GitHub</a>
 </p>
 <!-- xterm -->
-<script src="https://unpkg.com/xterm@3.6.0/dist/xterm.js"></script>
-<script src="https://unpkg.com/xterm@3.6.0/dist/addons/fit/fit.js"></script>
-<script src="https://unpkg.com/xterm@3.6.0/dist/addons/webLinks/webLinks.js"></script>
-<script src="https://unpkg.com/xterm@3.6.0/dist/addons/fullscreen/fullscreen.js"></script>
-<script src="https://unpkg.com/xterm@3.6.0/dist/addons/search/search.js"></script>
-<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.1.1/socket.io.js"></script>
+<script src="https://unpkg.com/xterm@4.11.0/lib/xterm.js"></script>
+<script src="https://unpkg.com/xterm-addon-fit@0.5.0/lib/xterm-addon-fit.js"></script>
+<script src="https://unpkg.com/xterm-addon-web-links@0.4.0/lib/xterm-addon-web-links.js"></script>
+<script src="https://unpkg.com/xterm-addon-search@0.8.0/lib/xterm-addon-sear
+ch.js"></script>
+<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/4.0.1/socket.io.min.js"></script>
 
 <script>
-  Terminal.applyAddon(fullscreen)
-  Terminal.applyAddon(fit)
-  Terminal.applyAddon(webLinks)
-  Terminal.applyAddon(search)
   const term = new Terminal({
         cursorBlink: true,
         macOptionIsMeta: true,
         scrollback: true,
     });
+  // https://github.com/xtermjs/xterm.js/issues/2941
+  const fit = new FitAddon.FitAddon();
+  term.loadAddon(fit);
+  term.loadAddon(new WebLinksAddon.WebLinksAddon());
+  term.loadAddon(new SearchAddon.SearchAddon());
+
   term.open(document.getElementById('terminal'));
-  term.fit()
+  fit.fit()
   term.resize(15, 50)
   console.log(`size: ${term.cols} columns, ${term.rows} rows`)
-  // term.toggleFullScreen(true)
-  term.fit()
+  fit.fit()
   term.write("Welcome to pyxterm.js!\nhttps://github.com/cs01/pyxterm.js\n")
-  term.on('key', (key, ev) => {
+  term.onKey((key, ev) => {
     console.log("pressed key", key)
     console.log("event", ev)
     socket.emit("pty-input", {"input": key})
@@ -69,7 +70,7 @@
   })
 
   function fitToscreen(){
-    term.fit()
+    fit.fit()
     socket.emit("resize", {"cols": term.cols, "rows": term.rows})
   }
 
diff --git a/requirements.txt b/requirements.txt
index dea330e..582436a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,13 +4,23 @@
 #
 #    pip-compile
 #
-click==7.0                # via flask
-flask-socketio==3.3.1
-flask==1.0.2              # via flask-socketio
-itsdangerous==1.1.0       # via flask
-jinja2==2.10              # via flask
-markupsafe==1.1.1         # via jinja2
-python-engineio==3.4.3    # via python-socketio
-python-socketio==3.1.2    # via flask-socketio
-six==1.12.0               # via python-engineio, python-socketio
-werkzeug==0.14.1          # via flask
+bidict==0.21.2
+    # via python-socketio
+click==7.1.2
+    # via flask
+flask-socketio==5.0.1
+    # via pyxtermjs (setup.py)
+flask==1.1.2
+    # via flask-socketio
+itsdangerous==1.1.0
+    # via flask
+jinja2==2.11.3
+    # via flask
+markupsafe==1.1.1
+    # via jinja2
+python-engineio==4.1.0
+    # via python-socketio
+python-socketio==5.2.1
+    # via flask-socketio
+werkzeug==1.0.1
+    # via flask
diff --git a/setup.py b/setup.py
index c82f7df..ac92cbb 100644
--- a/setup.py
+++ b/setup.py
@@ -59,7 +59,7 @@ def get_version() -> str:
     extras_require={},
     zip_safe=False,
     python_requires=">=3.6",
-    install_requires=["flask-socketio>=3.0, <=4.0"],
+    install_requires=["flask-socketio>=5.0, <6.0"],
     classifiers=[
         "Operating System :: OS Independent",
         "License :: OSI Approved :: MIT License",
