diff --git a/Lib/test/test_fcntl.py b/Lib/test/test_fcntl.py
old mode 100644
new mode 100755
index 5d4abe388f7828..d1fc737058970c
--- a/Lib/test/test_fcntl.py
+++ b/Lib/test/test_fcntl.py
@@ -5,6 +5,8 @@
 import struct
 import sys
 import unittest
+import textwrap
+import subprocess
 from test.support import (verbose, TESTFN, unlink, run_unittest, import_module,
                           cpython_only)
 
@@ -12,8 +14,6 @@
 fcntl = import_module('fcntl')
 
 
-# TODO - Write tests for flock() and lockf().
-
 def get_lockdata():
     try:
         os.O_LARGEFILE
@@ -138,6 +138,41 @@ def test_flock(self):
         self.assertRaises(ValueError, fcntl.flock, -1, fcntl.LOCK_SH)
         self.assertRaises(TypeError, fcntl.flock, 'spam', fcntl.LOCK_SH)
 
+    def test_lockf(self):
+
+        self.f = open(TESTFN, 'wb+')
+
+        fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
+
+        code = textwrap.dedent('''
+            try:
+                fcntl.lockf(open(self.f.name, self.f.mode), fcntl.LOCK_EX | fcntl.LOCK_NB)
+            except OSError as e:
+                if e.errno not in (errno.EACCES, errno.EAGAIN):
+                    raise
+                os.EX_OSERR
+            else:
+                os.EX_OK
+            finally:
+                os._exit()
+        ''')
+
+        args = (sys.executable, '-c', code)
+        proc = subprocess.run(args,
+                              stdout=subprocess.PIPE,
+                              stderr=subprocess.STDOUT)
+
+        fcntl.lockf(self.f, fcntl.LOCK_UN)
+
+    def test_lockf_errors(self):
+
+        self.f = open(TESTFN, 'wb+')
+
+        self.assertRaises(TypeError, fcntl.lockf, self.f, "foo")
+        self.assertRaises(TypeError, fcntl.lockf, self.f, fcntl.LOCK_UN, "foo")
+        self.assertRaises(ValueError, fcntl.lockf, self.f, -256)
+        self.assertRaises(ValueError, fcntl.lockf, self.f, 256)
+
     @cpython_only
     def test_flock_overflow(self):
         import _testcapi
@@ -145,8 +180,5 @@ def test_flock_overflow(self):
                           fcntl.LOCK_SH)
 
 
-def test_main():
-    run_unittest(TestFcntl)
-
 if __name__ == '__main__':
-    test_main()
+    unittest.main()