diff --git a/jupyter_remote_desktop_proxy/setup_websockify.py b/jupyter_remote_desktop_proxy/setup_websockify.py
index 7cdbd07b..2b9361d8 100644
--- a/jupyter_remote_desktop_proxy/setup_websockify.py
+++ b/jupyter_remote_desktop_proxy/setup_websockify.py
@@ -7,6 +7,12 @@
 
 
 def setup_websockify():
+    websockify = which('websockify')
+    if not websockify:
+        raise RuntimeError(
+            "websockify executable not found, please install websockify"
+        )
+
     vncserver = which('vncserver')
     if not vncserver:
         raise RuntimeError(