diff --git a/Lib/ctypes/test/__init__.py b/Lib/ctypes/test/__init__.py
index 24738ea..e2878f2 100644
--- a/Lib/ctypes/test/__init__.py
+++ b/Lib/ctypes/test/__init__.py
@@ -50,7 +50,7 @@
             if fnmatch.fnmatchcase(fnm, mask):
                 yield "%s.%s" % (package.__name__, os.path.splitext(fnm)[0])
 
-def get_tests(package, mask, verbosity, exclude):
+def get_tests(package, mask, verbosity, exclude=()):
     """Return a list of skipped test modules, and a list of test cases."""
     tests = []
     skipped = []
diff --git a/Lib/ctypes/test/runtests.py b/Lib/ctypes/test/runtests.py
index 14d7caa..ec31fc8 100644
--- a/Lib/ctypes/test/runtests.py
+++ b/Lib/ctypes/test/runtests.py
@@ -8,6 +8,8 @@
          Add resources to the lits of allowed resources. '*' allows all
          resources.
   -v     verbose mode: print the test currently executed
+  -x<test1[,test2...]>
+         Exclude specified tests.
   mask   mask to select filenames containing testcases, wildcards allowed
 """
 import sys