diff --git a/adafruit_itertools/__init__.py b/adafruit_itertools/__init__.py
index 82234fb..f739f28 100644
--- a/adafruit_itertools/__init__.py
+++ b/adafruit_itertools/__init__.py
@@ -263,9 +263,7 @@ class groupby:
     # [list(g) for k, g in groupby('AAAABBBCCD')] --> AAAA BBB CC D
 
     def __init__(self, iterable, key=None):
-        if key is None:
-            key = lambda x: x
-        self.keyfunc = key
+        self.keyfunc = key if key is not None else lambda x: x
         self.it = iter(iterable)
         self.tgtkey = self.currkey = self.currvalue = object()