diff --git a/erynrl/interface/window/info.py b/erynrl/interface/window/info.py
index 6252fdc..1b21940 100644
--- a/erynrl/interface/window/info.py
+++ b/erynrl/interface/window/info.py
@@ -4,6 +4,8 @@
 Declares the InfoWindow.
 '''
 
+from tcod.console import Console
+
 from . import Window
 from ..color import HealthBar
 from ..percentage_bar import PercentageBar
@@ -34,7 +36,7 @@ class InfoWindow(Window):
 
         self.hit_points_bar.percent_filled = hp / max_hp
 
-    def draw(self, console):
+    def draw(self, console: Console):
         super().draw(console)
 
         drawable_bounds = self.drawable_bounds
diff --git a/erynrl/interface/window/message_log.py b/erynrl/interface/window/message_log.py
index 13d6091..df7d6ea 100644
--- a/erynrl/interface/window/message_log.py
+++ b/erynrl/interface/window/message_log.py
@@ -4,6 +4,8 @@
 Declares the MessageLogWindow.
 '''
 
+from tcod.console import Console
+
 from . import Window
 from ...geometry import Rect
 from ...messages import MessageLog
@@ -16,6 +18,6 @@ class MessageLogWindow(Window):
         super().__init__(bounds, framed=True)
         self.message_log = message_log
 
-    def draw(self, console):
+    def draw(self, console: Console):
         super().draw(console)
         self.message_log.render_to_console(console, self.drawable_bounds)
diff --git a/erynrl/monsters.py b/erynrl/monsters.py
index 2333ba8..06bbdcb 100644
--- a/erynrl/monsters.py
+++ b/erynrl/monsters.py
@@ -4,9 +4,11 @@
 the dungeon.'''
 
 from dataclasses import dataclass
-from typing import Tuple
+from typing import Optional, Tuple
 
 # pylint: disable=too-many-instance-attributes
+
+
 @dataclass(frozen=True)
 class Species:
     '''A kind of monster.
@@ -35,7 +37,8 @@ class Species:
     attack_power: int
     defense: int
     foreground_color: Tuple[int, int, int]
-    background_color: Tuple[int, int, int] = None
+    background_color: Optional[Tuple[int, int, int]] = None
+
 
 Orc = Species(name='Orc', symbol='o',
               foreground_color=(63, 127, 63),