diff --git a/Lib/plat-mac/aetypes.py b/Lib/plat-mac/aetypes.py
index c60b39c..65b59ad 100644
--- a/Lib/plat-mac/aetypes.py
+++ b/Lib/plat-mac/aetypes.py
@@ -430,7 +430,7 @@
     return isinstance(x, ObjectSpecifier)
 
 
-# Backwards compatability, sigh...
+# Backwards compatibility, sigh...
 class Property(ObjectSpecifier):
 
     def __init__(self, which, fr = None, want='prop'):
diff --git a/Lib/plat-mac/macostools.py b/Lib/plat-mac/macostools.py
index 06bc92f..f7ce468 100644
--- a/Lib/plat-mac/macostools.py
+++ b/Lib/plat-mac/macostools.py
@@ -13,7 +13,7 @@
 try:
     openrf = MacOS.openrf
 except AttributeError:
-    # Backward compatability
+    # Backward compatibility
     openrf = open
 
 Error = 'macostools.Error'