diff --git a/freqtrade/configuration.py b/freqtrade/configuration.py
index 43d0a0bf9..14c29e8fd 100644
--- a/freqtrade/configuration.py
+++ b/freqtrade/configuration.py
@@ -5,7 +5,7 @@ This module contains the configuration class
 import json
 import logging
 from argparse import Namespace
-from typing import Dict, Any
+from typing import Optional, Dict, Any
 from jsonschema import Draft4Validator, validate
 from jsonschema.exceptions import ValidationError, best_match
 import ccxt
@@ -23,7 +23,7 @@ class Configuration(object):
     """
     def __init__(self, args: Namespace) -> None:
         self.args = args
-        self.config = None
+        self.config: Optional[Dict[str, Any]] = None
 
     def load_config(self) -> Dict[str, Any]:
         """
@@ -192,7 +192,7 @@ class Configuration(object):
             validate(conf, constants.CONF_SCHEMA)
             return conf
         except ValidationError as exception:
-            logger.fatal(
+            logger.critical(
                 'Invalid configuration. See config.json.example. Reason: %s',
                 exception
             )
diff --git a/freqtrade/misc.py b/freqtrade/misc.py
index 225fb32df..90a1db42b 100644
--- a/freqtrade/misc.py
+++ b/freqtrade/misc.py
@@ -83,7 +83,7 @@ def file_dump_json(filename, data, is_zip=False) -> None:
             json.dump(data, fp, default=str)
 
 
-def format_ms_time(date: str) -> str:
+def format_ms_time(date: int) -> str:
     """
     convert MS date to readable format.
     : epoch-string in ms
diff --git a/freqtrade/optimize/__init__.py b/freqtrade/optimize/__init__.py
index f6f1ba47a..58a4b07fe 100644
--- a/freqtrade/optimize/__init__.py
+++ b/freqtrade/optimize/__init__.py
@@ -4,8 +4,8 @@ import gzip
 import json
 import logging
 import os
+from typing import Optional, List, Dict, Tuple, Any
 import arrow
-from typing import Optional, List, Dict, Tuple
 
 from freqtrade import misc, constants
 from freqtrade.exchange import get_ticker_history
@@ -139,7 +139,9 @@ def download_pairs(datadir, pairs: List[str],
 
 def load_cached_data_for_updating(filename: str,
                                   tick_interval: str,
-                                  timerange: Optional[Tuple[Tuple, int, int]]) -> Tuple[list, int]:
+                                  timerange: Optional[Tuple[Tuple, int, int]]) -> Tuple[
+                                                                                  List[Any],
+                                                                                  Optional[int]]:
     """
     Load cached data and choose what part of the data should be updated
     """
diff --git a/freqtrade/persistence.py b/freqtrade/persistence.py
index 2d497662e..c10599b3c 100644
--- a/freqtrade/persistence.py
+++ b/freqtrade/persistence.py
@@ -5,7 +5,7 @@ This module contains the class to persist trades into SQLite
 import logging
 from datetime import datetime
 from decimal import Decimal, getcontext
-from typing import Dict, Optional
+from typing import Dict, Optional, Any
 
 import arrow
 from sqlalchemy import (Boolean, Column, DateTime, Float, Integer, String,
@@ -21,7 +21,7 @@ from sqlalchemy import inspect
 logger = logging.getLogger(__name__)
 
 _CONF = {}
-_DECL_BASE = declarative_base()
+_DECL_BASE = declarative_base()  # type: Any
 
 
 def init(config: dict, engine: Optional[Engine] = None) -> None: