diff --git a/whispering/cli.py b/whispering/cli.py
index 4183860..33e3e13 100644
--- a/whispering/cli.py
+++ b/whispering/cli.py
@@ -224,6 +224,19 @@ def show_devices():
             print(f"{i}: {device['name']}")
 
 
+def check_invalid_arg(opts):
+    ngs = []
+    if opts.mode == Mode.server.value:
+        ngs = [
+            "mic",
+            "allow_padding",
+        ]
+    for ng in ngs:
+        if vars(opts).get(ng) not in {None, False}:
+            sys.stderr.write(f"{ng} is not accepted option for {opts.mode} mode\n")
+            sys.exit(1)
+
+
 def main() -> None:
     opts = get_opts()
 
@@ -242,13 +255,20 @@ def main() -> None:
     ):
         opts.mode = Mode.server.value
 
+    check_invalid_arg(opts)
     if opts.mode == Mode.client.value:
         assert opts.language is None
         assert opts.model is None
+        ctx: Context = get_context(opts=opts)
         try:
             asyncio.run(
                 run_websocket_client(
-                    opts=opts,
+                    sd_device=opts.mic,
+                    num_block=opts.num_block,
+                    host=opts.host,
+                    port=opts.port,
+                    no_progress=opts.no_progress,
+                    ctx=ctx,
                 )
             )
         except KeyboardInterrupt:
@@ -257,13 +277,11 @@ def main() -> None:
         assert opts.language is not None
         assert opts.model is not None
         wsp = get_wshiper(opts=opts)
-        ctx: Context = get_context(opts=opts)
         asyncio.run(
             serve_with_websocket(
                 wsp=wsp,
                 host=opts.host,
                 port=opts.port,
-                ctx=ctx,
             )
         )
     else:
diff --git a/whispering/serve.py b/whispering/serve.py
index c0d2e16..1399a3c 100644
--- a/whispering/serve.py
+++ b/whispering/serve.py
@@ -1,7 +1,9 @@
 #!/usr/bin/env python3
 
 import asyncio
+import json
 from logging import getLogger
+from typing import Optional
 
 import numpy as np
 import websockets
@@ -14,11 +16,8 @@ logger = getLogger(__name__)
 
 async def serve_with_websocket_main(websocket):
     global g_wsp
-    global g_ctx
     idx: int = 0
-    ctx: Context = g_ctx.copy(
-        deep=True,
-    )
+    ctx: Optional[Context] = None
 
     while True:
         logger.debug(f"Audio #: {idx}")
@@ -33,6 +32,15 @@ async def serve_with_websocket_main(websocket):
 
         logger.debug(f"Message size: {len(message)}")
         audio = np.frombuffer(message, dtype=np.float32)
+        if ctx is None:
+            await websocket.send(
+                json.dumps(
+                    {
+                        "error": "no context",
+                    }
+                )
+            )
+            return
         for chunk in g_wsp.transcribe(
             audio=audio,  # type: ignore
             ctx=ctx,
@@ -46,14 +54,11 @@ async def serve_with_websocket(
     wsp: WhisperStreamingTranscriber,
     host: str,
     port: int,
-    ctx: Context,
 ):
     logger.info(f"Serve at {host}:{port}")
     logger.info("Make secure with your responsibility!")
     global g_wsp
-    global g_ctx
     g_wsp = wsp
-    g_ctx = ctx
 
     try:
         async with websockets.serve(  # type: ignore
diff --git a/whispering/websocket_client.py b/whispering/websocket_client.py
index 26540ac..f59de38 100644
--- a/whispering/websocket_client.py
+++ b/whispering/websocket_client.py
@@ -8,6 +8,7 @@ import websockets
 from whisper.audio import N_FRAMES, SAMPLE_RATE
 
 from whispering.schema import ParsedChunk
+from whispering.transcriber import Context
 
 logger = getLogger(__name__)
 
@@ -24,6 +25,7 @@ async def transcribe_from_mic_and_send(
     num_block: int,
     host: str,
     port: int,
+    ctx: Context,
 ) -> None:
     uri = f"ws://{host}:{port}"
 
@@ -67,15 +69,24 @@ async def transcribe_from_mic_and_send(
                 idx += 1
 
 
-async def run_websocket_client(*, opts) -> None:
+async def run_websocket_client(
+    *,
+    sd_device: Optional[Union[int, str]],
+    num_block: int,
+    host: str,
+    port: int,
+    ctx: Context,
+    no_progress: bool,
+) -> None:
     global q
     global loop
     loop = asyncio.get_running_loop()
     q = asyncio.Queue()
 
     await transcribe_from_mic_and_send(
-        sd_device=opts.mic,
-        num_block=opts.num_block,
-        host=opts.host,
-        port=opts.port,
+        sd_device=sd_device,
+        num_block=num_block,
+        host=host,
+        port=port,
+        ctx=ctx,
     )