diff --git a/adafruit_il91874.py b/adafruit_il91874.py
index e6cc35a..9fec1ec 100644
--- a/adafruit_il91874.py
+++ b/adafruit_il91874.py
@@ -69,7 +69,7 @@
 class IL91874(displayio.EPaperDisplay):
     """IL91874 display driver"""
 
-    def __init__(self, bus, **kwargs):
+    def __init__(self, bus: displayio.FourWire, **kwargs) -> None:
         start_sequence = bytearray(_START_SEQUENCE)
 
         width = kwargs["width"]