diff --git a/Lib/ctypes/test/test_bytes.py b/Lib/ctypes/test/test_bytes.py
index 57cf365ea2f..ee49c456e8e 100644
--- a/Lib/ctypes/test/test_bytes.py
+++ b/Lib/ctypes/test/test_bytes.py
@@ -45,7 +45,6 @@ class BytesTest(unittest.TestCase):
                 _type_ = "X"
 
             BSTR("abc")
-            BSTR(b"abc")
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/ctypes/test/test_loading.py b/Lib/ctypes/test/test_loading.py
index 07b69ec2011..4029b463bcd 100644
--- a/Lib/ctypes/test/test_loading.py
+++ b/Lib/ctypes/test/test_loading.py
@@ -97,7 +97,7 @@ class LoaderTest(unittest.TestCase):
             self.assertEqual(0, advapi32.CloseEventLog(None))
             windll.kernel32.GetProcAddress.argtypes = c_void_p, c_char_p
             windll.kernel32.GetProcAddress.restype = c_void_p
-            proc = windll.kernel32.GetProcAddress(advapi32._handle, "CloseEventLog")
+            proc = windll.kernel32.GetProcAddress(advapi32._handle, b"CloseEventLog")
             self.assertTrue(proc)
             # This is the real test: call the function via 'call_function'
             self.assertEqual(0, call_function(proc, (None,)))
diff --git a/Lib/ctypes/test/test_random_things.py b/Lib/ctypes/test/test_random_things.py
index 4e9f08fb70b..515acf509a6 100644
--- a/Lib/ctypes/test/test_random_things.py
+++ b/Lib/ctypes/test/test_random_things.py
@@ -18,7 +18,7 @@ if sys.platform == "win32":
             windll.kernel32.GetProcAddress.restype = c_void_p
 
             hdll = windll.kernel32.LoadLibraryA(b"kernel32")
-            funcaddr = windll.kernel32.GetProcAddress(hdll, "GetModuleHandleA")
+            funcaddr = windll.kernel32.GetProcAddress(hdll, b"GetModuleHandleA")
 
             self.assertEqual(call_function(funcaddr, (None,)),
                                  windll.kernel32.GetModuleHandleA(None))