diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index e9fdb07..46ad209 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -473,7 +473,9 @@
         # force CreateFile to fail with ERROR_ACCESS_DENIED.
         DETACHED_PROCESS = 8
         subprocess.check_call(
-            ['icacls.exe', fname, '/deny', 'Users:(S)'],
+            # bpo-30584: Use security identifier *S-1-5-32-545 instead
+            # of localized "Users" to not depend on the locale.
+            ['icacls.exe', fname, '/deny', '*S-1-5-32-545:(S)'],
             creationflags=DETACHED_PROCESS
         )
         result = os.stat(fname)
diff --git a/Misc/ACKS b/Misc/ACKS
index bbdc69d..c2ebf7f 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1121,6 +1121,7 @@
 Michele Orrù
 Tomáš Orsava
 Oleg Oshmyan
+Denis Osipov
 Denis S. Otkidach
 Peter Otten
 Michael Otteneder