diff --git a/build/mac/tweak_info_plist.py b/build/mac/tweak_info_plist.py
index 5ad93b9c1235..771c921a21c6 100644
--- a/build/mac/tweak_info_plist.py
+++ b/build/mac/tweak_info_plist.py
@@ -29,6 +29,7 @@
 
 def _ConvertPlist(source_plist, output_plist, fmt):
     """Convert |source_plist| to |fmt| and save as |output_plist|."""
+    assert sys.version_info.major == 2, "Use plistlib directly in Python 3"
     return subprocess.call(
         ['plutil', '-convert', fmt, '-o', output_plist, source_plist])
 
@@ -82,10 +83,14 @@ def Main():
     # Read the plist into its parsed format. Convert the file to 'xml1' as
     # plistlib only supports that format in Python 2.7.
     with tempfile.NamedTemporaryFile() as temp_info_plist:
-        retcode = _ConvertPlist(args.plist_path, temp_info_plist.name, 'xml1')
-        if retcode != 0:
-            return retcode
-        plist = plistlib.readPlist(temp_info_plist.name)
+        if sys.version_info.major == 2:
+            retcode = _ConvertPlist(args.plist_path, temp_info_plist.name, 'xml1')
+            if retcode != 0:
+                return retcode
+            plist = plistlib.readPlist(temp_info_plist.name)
+        else:
+            with open(args.plist_path, 'rb') as f:
+                plist = plistlib.load(f)
 
     output_path = args.plist_path
     if args.plist_output is not None:
@@ -109,12 +114,15 @@ def Main():
     plist['SUEnableSystemProfiling'] = False
 
     # Now that all keys have been mutated, rewrite the file.
-    with tempfile.NamedTemporaryFile() as temp_info_plist:
-        plistlib.writePlist(plist, temp_info_plist.name)
-
-        # Convert Info.plist to the format requested by the --format flag. Any
-        # format would work on Mac but iOS requires specific format.
-        return _ConvertPlist(temp_info_plist.name, output_path, args.format)
+    # Convert Info.plist to the format requested by the --format flag. Any
+    # format would work on Mac but iOS requires specific format.
+    if sys.version_info.major == 2:
+        with tempfile.NamedTemporaryFile() as temp_info_plist:
+            plistlib.writePlist(plist, temp_info_plist.name)
+            return _ConvertPlist(temp_info_plist.name, output_path, args.format)
+    with open(output_path, 'wb') as f:
+        plist_format = {'binary1': plistlib.FMT_BINARY, 'xml1': plistlib.FMT_XML}
+        plistlib.dump(plist, f, fmt=plist_format[args.format])
 
 
 if __name__ == '__main__':