diff --git a/bfxapi/client.py b/bfxapi/client.py
index 4a7bbdf..fe86615 100644
--- a/bfxapi/client.py
+++ b/bfxapi/client.py
@@ -1,11 +1,18 @@
-from typing import List, Literal, Optional
+from typing import \
+    TYPE_CHECKING, TypedDict, List, Literal, Optional
 
 from bfxapi._utils.logger import ColorLogger
 
+from bfxapi.exceptions import IncompleteCredentialError
+
 from bfxapi.rest import BfxRestInterface
 from bfxapi.websocket import BfxWebSocketClient
 from bfxapi.urls import REST_HOST, WSS_HOST
 
+if TYPE_CHECKING:
+    _Credentials = TypedDict("_Credentials", \
+        { "api_key": str, "api_secret": str, "filters": Optional[List[str]] })
+
 class Client:
     def __init__(
             self,
@@ -15,16 +22,28 @@ class Client:
             rest_host: str = REST_HOST,
             wss_host: str = WSS_HOST,
             filters: Optional[List[str]] = None,
-            wss_timeout: Optional[float] = 60 * 15,
+            timeout: Optional[float] = 60 * 15,
             log_filename: Optional[str] = None,
             log_level: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"] = "INFO"
     ) -> None:
+        credentials: Optional["_Credentials"] = None
+
+        if api_key and api_secret:
+            credentials = \
+                { "api_key": api_key, "api_secret": api_secret, "filters": filters }
+        elif api_key:
+            raise IncompleteCredentialError( \
+                "You must provide both an API-KEY and an API-SECRET (missing API-KEY).")
+        elif api_secret:
+            raise IncompleteCredentialError( \
+                "You must provide both an API-KEY and an API-SECRET (missing API-SECRET).")
+
+        self.rest = BfxRestInterface(rest_host, api_key, api_secret)
+
         logger = ColorLogger("bfxapi", level=log_level)
 
         if log_filename:
             logger.register(filename=log_filename)
 
-        self.rest = BfxRestInterface(rest_host, api_key, api_secret)
-
-        self.wss = BfxWebSocketClient(wss_host, api_key, api_secret,
-            filters=filters, wss_timeout=wss_timeout, logger=logger)
+        self.wss = BfxWebSocketClient(wss_host, \
+            credentials=credentials, timeout=timeout, logger=logger)
diff --git a/bfxapi/exceptions.py b/bfxapi/exceptions.py
index 136f5f1..b636119 100644
--- a/bfxapi/exceptions.py
+++ b/bfxapi/exceptions.py
@@ -6,3 +6,8 @@ class BfxBaseException(Exception):
     """
     Base class for every custom exception in bfxapi/rest/exceptions.py and bfxapi/websocket/exceptions.py.
     """
+
+class IncompleteCredentialError(BfxBaseException):
+    """
+    This error indicates an incomplete credential object (missing api-key or api-secret).
+    """
diff --git a/bfxapi/websocket/_client/bfx_websocket_client.py b/bfxapi/websocket/_client/bfx_websocket_client.py
index 8ff481f..dd02469 100644
--- a/bfxapi/websocket/_client/bfx_websocket_client.py
+++ b/bfxapi/websocket/_client/bfx_websocket_client.py
@@ -36,13 +36,12 @@ from .bfx_websocket_bucket import BfxWebSocketBucket
 from .bfx_websocket_inputs import BfxWebSocketInputs
 
 if TYPE_CHECKING:
+    from bfxapi.client import _Credentials
+
     from asyncio import Task
 
     _T = TypeVar("_T", bound=Callable[..., None])
 
-    _Credentials = TypedDict("_Credentials", \
-        { "api_key": str, "api_secret": str, "filters": Optional[List[str]] })
-
     _Reconnection = TypedDict("_Reconnection",
         { "attempts": int, "reason": str, "timestamp": datetime })