diff --git a/greentest/test__coros_semaphore.py b/greentest/test__coros_semaphore.py
new file mode 100644
index 0000000..e5ad3aa
--- /dev/null
+++ b/greentest/test__coros_semaphore.py
@@ -0,0 +1,30 @@
+from __future__ import with_statement
+import unittest
+from eventlet import api, coros
+
+class TestSemaphore(unittest.TestCase):
+
+    def test_bounded(self):
+        # this was originally semaphore's doctest
+        sem = coros.BoundedSemaphore(2, limit=3)
+        self.assertEqual(sem.acquire(), True)
+        self.assertEqual(sem.acquire(), True)
+        api.spawn(sem.release)
+        self.assertEqual(sem.acquire(), True)
+        self.assertEqual(0, sem.counter)
+        sem.release()
+        sem.release()
+        sem.release()
+        api.spawn(sem.acquire)
+        sem.release()
+        self.assertEqual(3, sem.counter)
+   
+    def test_bounded_with_zero_limit(self):
+        sem = coros.semaphore(0, 0)
+        api.spawn(sem.acquire)
+        with api.timeout(0.001):
+            sem.release()
+
+
+if __name__=='__main__':
+    unittest.main()