diff --git a/Makefile b/Makefile
index 417a348a9fd3f3b744afcd507c8f39dfd7b842b9..f8035f87252c475cf72c290281906698d9b62122 100644
--- a/Makefile
+++ b/Makefile
@@ -17,4 +17,4 @@ mypy:
 
 # check code errors
 pylint:
-	pylint --disable=C,R0913,R0903,R0902,R0914,R0912,R0915 --enable=C0121,C0202,C0321 --jobs=0 duniterpy/
+	pylint --disable=C,R0913,R0903,R0902,R0914,R0912,R0915,W0613 --enable=C0121,C0202,C0321 --jobs=0 duniterpy/
diff --git a/duniterpy/api/client.py b/duniterpy/api/client.py
index d16c0d1d8bba2e08bd46109c105ed850947c36e5..a1f102a09387e5f384122140dfc8b63f287dcb4a 100644
--- a/duniterpy/api/client.py
+++ b/duniterpy/api/client.py
@@ -236,12 +236,13 @@ class Client:
             await parse_response(response, schema)
 
         # return the chosen type
+        result = response  # type: Any
         if rtype == RESPONSE_TEXT:
-            response = await response.text()
+            result = await response.text()
         elif rtype == RESPONSE_JSON:
-            response = await response.json()
+            result = await response.json()
 
-        return response
+        return result
 
     async def post(self, url_path: str, params: dict = None, rtype: str = RESPONSE_JSON, schema: dict = None) -> Any:
         """
@@ -267,12 +268,13 @@ class Client:
             await parse_response(response, schema)
 
         # return the chosen type
+        result = response  # type: Any
         if rtype == RESPONSE_TEXT:
-            response = await response.text()
+            result = await response.text()
         elif rtype == RESPONSE_JSON:
-            response = await response.json()
+            result = await response.json()
 
-        return response
+        return result
 
     def connect_ws(self, path: str) -> _WSRequestContextManager:
         """
diff --git a/duniterpy/documents/transaction.py b/duniterpy/documents/transaction.py
index 5ee294049010ffeb38e0937c6b873523e3ef7a93..bdd5075c25c8a5a8d8c74558c63ffc8b02a911d7 100644
--- a/duniterpy/documents/transaction.py
+++ b/duniterpy/documents/transaction.py
@@ -339,7 +339,7 @@ class UnlockParameter:
         :param parameter: Parameter string
         :return:
         """
-        result = None
+        result = None  # type: Optional[Union[SIGParameter, XHXParameter]]
         sig_param = SIGParameter.from_parameter(parameter)
         if sig_param:
             result = sig_param