diff --git a/Lib/platform.py b/Lib/platform.py
index 48b81ac..11b501e 100755
--- a/Lib/platform.py
+++ b/Lib/platform.py
@@ -649,7 +649,8 @@
     except ImportError:
         return None
 
-    pl = plistlib.readPlist(fn)
+    with open(fn, 'rb') as f:
+        pl = plistlib.load(f)
     release = pl['ProductVersion']
     versioninfo = ('', '', '')
     machine = os.uname().machine
diff --git a/Misc/NEWS b/Misc/NEWS
index d6232d3..50765c9 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -65,6 +65,8 @@
 
 - Issue #20072: Fixed multiple errors in tkinter with wantobjects is False.
 
+- Issue #20229: Avoid plistlib deprecation warning in platform.mac_ver().
+
 IDLE
 ----