diff --git a/examples/gl_interop_demo.py b/examples/gl_interop_demo.py
index 02469762c5cae702b0367212732acf40fbbb0573..8b1e248ee2e7eaabb5a5125a051d873c7e5f94d2 100644
--- a/examples/gl_interop_demo.py
+++ b/examples/gl_interop_demo.py
@@ -37,6 +37,10 @@ def initialize():
         props.append(
                 (ctx_props.WGL_HDC_KHR, 
                     WGL.wglGetCurrentDC()))
+    else:
+        raise NotImplementedError("platform '%s' not yet supported" 
+                % sys.platform)
+
     ctx = cl.Context(properties=props)
 
     glClearColor(1, 1, 1, 1)