diff --git a/whisper_live/server.py b/whisper_live/server.py
index 2accaac..b6efc77 100644
--- a/whisper_live/server.py
+++ b/whisper_live/server.py
@@ -4,6 +4,9 @@ import threading
 import json
 import functools
 import logging
+from enum import Enum
+from typing import List, Optional
+
 import torch
 import numpy as np
 from websockets.sync.server import serve
@@ -121,6 +124,25 @@ class ClientManager:
         return False
 
 
+class BackendType(Enum):
+    FASTER_WHISPER = "faster_whisper"
+    TENSORRT = "tensorrt"
+
+    @staticmethod
+    def valid_types() -> List[str]:
+        return [backend_type.value for backend_type in BackendType]
+
+    @staticmethod
+    def is_valid(backend: str) -> bool:
+        return backend in BackendType.valid_types()
+
+    def is_faster_whisper(self) -> bool:
+        return self == BackendType.FASTER_WHISPER
+
+    def is_tensorrt(self) -> bool:
+        return self == BackendType.TENSORRT
+
+
 class TranscriptionServer:
     RATE = 16000
 
@@ -134,7 +156,9 @@ class TranscriptionServer:
         self, websocket, options, faster_whisper_custom_model_path,
         whisper_tensorrt_path, trt_multilingual
     ):
-        if self.backend == "tensorrt":
+        client: Optional[ServeClientBase] = None
+
+        if self.backend.is_tensorrt():
             try:
                 client = ServeClientTensorRT(
                     websocket,
@@ -155,9 +179,9 @@ class TranscriptionServer:
                     "message": "TensorRT-LLM not supported on Server yet. "
                                "Reverting to available backend: 'faster_whisper'"
                 }))
-                self.backend = "faster_whisper"
+                self.backend = BackendType.FASTER_WHISPER
 
-        if self.backend == "faster_whisper":
+        if self.backend.is_faster_whisper():
             if faster_whisper_custom_model_path is not None and os.path.exists(faster_whisper_custom_model_path):
                 logging.info(f"Using custom model {faster_whisper_custom_model_path}")
                 options["model"] = faster_whisper_custom_model_path
@@ -174,6 +198,9 @@ class TranscriptionServer:
             )
             logging.info("Running faster_whisper backend.")
 
+        if client is None:
+            raise ValueError(f"Backend type {self.backend.value} not recognised or not handled.")
+
         self.client_manager.add_client(websocket, client)
 
     def get_audio_from_websocket(self, websocket):
@@ -202,7 +229,7 @@ class TranscriptionServer:
                 websocket.close()
                 return False  # Indicates that the connection should not continue
 
-            if self.backend == "tensorrt":
+            if self.backend.is_tensorrt():
                 self.vad_detector = VoiceActivityDetector(frame_rate=self.RATE)
             self.initialize_client(websocket, options, faster_whisper_custom_model_path,
                                    whisper_tensorrt_path, trt_multilingual)
@@ -221,11 +248,11 @@ class TranscriptionServer:
         frame_np = self.get_audio_from_websocket(websocket)
         client = self.client_manager.get_client(websocket)
         if frame_np is False:
-            if self.backend == "tensorrt":
+            if self.backend.is_tensorrt():
                 client.set_eos(True)
             return False
 
-        if self.backend == "tensorrt":
+        if self.backend.is_tensorrt():
             voice_active = self.voice_activity(websocket, frame_np)
             if voice_active:
                 self.no_voice_activity_chunks = 0
@@ -238,7 +265,7 @@ class TranscriptionServer:
 
     def recv_audio(self,
                    websocket,
-                   backend="faster_whisper",
+                   backend: BackendType = BackendType.FASTER_WHISPER,
                    faster_whisper_custom_model_path=None,
                    whisper_tensorrt_path=None,
                    trt_multilingual=False):
@@ -311,10 +338,12 @@ class TranscriptionServer:
                 # TODO: load model initially
             else:
                 logging.info("Single model mode currently only works with custom models.")
+        if not BackendType.is_valid(backend):
+            raise ValueError(f"{backend} is not a valid backend type. Choose backend from {BackendType.valid_types()}")
         with serve(
             functools.partial(
                 self.recv_audio,
-                backend=backend,
+                backend=BackendType(backend),
                 faster_whisper_custom_model_path=faster_whisper_custom_model_path,
                 whisper_tensorrt_path=whisper_tensorrt_path,
                 trt_multilingual=trt_multilingual