diff --git a/Lib/plistlib.py b/Lib/plistlib.py
index 83b214e9dc4..2eeebe4c9a4 100644
--- a/Lib/plistlib.py
+++ b/Lib/plistlib.py
@@ -611,7 +611,7 @@ def _count_to_size(count):
     elif count < 1 << 16:
         return 2
 
-    elif count << 1 << 32:
+    elif count < 1 << 32:
         return 4
 
     else:
diff --git a/Misc/NEWS.d/next/Library/2020-11-03-09-22-56.bpo-42249.vfNO2u.rst b/Misc/NEWS.d/next/Library/2020-11-03-09-22-56.bpo-42249.vfNO2u.rst
new file mode 100644
index 00000000000..071a0fdda1f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-11-03-09-22-56.bpo-42249.vfNO2u.rst
@@ -0,0 +1 @@
+Fixed writing binary Plist files larger than 4 GiB.