diff --git a/freqtrade/exchange/common.py b/freqtrade/exchange/common.py
index 4355662a8..a9f03ba1a 100644
--- a/freqtrade/exchange/common.py
+++ b/freqtrade/exchange/common.py
@@ -2,6 +2,7 @@ import asyncio
 import logging
 import time
 from functools import wraps
+from typing import Any, Callable, Optional, TypeVar, cast, overload
 
 from freqtrade.exceptions import DDosProtection, RetryableOrderError, TemporaryError
 from freqtrade.mixins import LoggingMixin
@@ -133,8 +134,22 @@ def retrier_async(f):
     return wrapper
 
 
-def retrier(_func=None, retries=API_RETRY_COUNT):
-    def decorator(f):
+F = TypeVar('F', bound=Callable[..., Any])
+
+
+# Type shenanigans
+@overload
+def retrier(_func: F) -> F:
+    ...
+
+
+@overload
+def retrier(*, retries=API_RETRY_COUNT) -> Callable[[F], F]:
+    ...
+
+
+def retrier(_func: Optional[F] = None, *, retries=API_RETRY_COUNT):
+    def decorator(f: F) -> F:
         @wraps(f)
         def wrapper(*args, **kwargs):
             count = kwargs.pop('count', retries)
@@ -155,7 +170,7 @@ def retrier(_func=None, retries=API_RETRY_COUNT):
                 else:
                     logger.warning(msg + 'Giving up.')
                     raise ex
-        return wrapper
+        return cast(F, wrapper)
     # Support both @retrier and @retrier(retries=2) syntax
     if _func is None:
         return decorator
diff --git a/freqtrade/exchange/exchange.py b/freqtrade/exchange/exchange.py
index 2fa397300..b25886868 100644
--- a/freqtrade/exchange/exchange.py
+++ b/freqtrade/exchange/exchange.py
@@ -1164,7 +1164,7 @@ class Exchange:
             raise OperationalException(e) from e
 
     @retrier(retries=API_FETCH_ORDER_RETRY_COUNT)
-    def fetch_order(self, order_id: str, pair: str, params={}) -> Dict:
+    def fetch_order(self, order_id: str, pair: str, params: Dict = {}) -> Dict:
         if self._config['dry_run']:
             return self.fetch_dry_run_order(order_id)
         try:
@@ -1212,7 +1212,7 @@ class Exchange:
                 and order.get('filled') == 0.0)
 
     @retrier
-    def cancel_order(self, order_id: str, pair: str, params={}) -> Dict:
+    def cancel_order(self, order_id: str, pair: str, params: Dict = {}) -> Dict:
         if self._config['dry_run']:
             try:
                 order = self.fetch_dry_run_order(order_id)
diff --git a/freqtrade/exchange/ftx.py b/freqtrade/exchange/ftx.py
index 65c2a53ca..9ee6894f1 100644
--- a/freqtrade/exchange/ftx.py
+++ b/freqtrade/exchange/ftx.py
@@ -104,7 +104,7 @@ class Ftx(Exchange):
             raise OperationalException(e) from e
 
     @retrier(retries=API_FETCH_ORDER_RETRY_COUNT)
-    def fetch_stoploss_order(self, order_id: str, pair: str) -> Dict:
+    def fetch_stoploss_order(self, order_id: str, pair: str, params: Dict = {}) -> Dict:
         if self._config['dry_run']:
             return self.fetch_dry_run_order(order_id)
 
@@ -145,7 +145,7 @@ class Ftx(Exchange):
             raise OperationalException(e) from e
 
     @retrier
-    def cancel_stoploss_order(self, order_id: str, pair: str) -> Dict:
+    def cancel_stoploss_order(self, order_id: str, pair: str, params: Dict = {}) -> Dict:
         if self._config['dry_run']:
             return {}
         try:
diff --git a/freqtrade/exchange/gateio.py b/freqtrade/exchange/gateio.py
index 609cf4901..4147e8290 100644
--- a/freqtrade/exchange/gateio.py
+++ b/freqtrade/exchange/gateio.py
@@ -71,14 +71,14 @@ class Gateio(Exchange):
                             }
         return trades
 
-    def fetch_stoploss_order(self, order_id: str, pair: str, params={}) -> Dict:
+    def fetch_stoploss_order(self, order_id: str, pair: str, params: Dict = {}) -> Dict:
         return self.fetch_order(
             order_id=order_id,
             pair=pair,
             params={'stop': True}
         )
 
-    def cancel_stoploss_order(self, order_id: str, pair: str, params={}) -> Dict:
+    def cancel_stoploss_order(self, order_id: str, pair: str, params: Dict = {}) -> Dict:
         return self.cancel_order(
             order_id=order_id,
             pair=pair,