# HG changeset patch
# Parent 516576f5f9dc32d03c23bcdf9d393b80dc2754b9

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -599,6 +599,24 @@
             time.sleep(0.01)
         self.assertIn(LOOKING_FOR, repr(t)) # we waited at least 5 seconds
 
+    def test_BoundedSemaphore_limit(self):
+        # BoundedSemaphore should raise ValueError if released too often.
+        for limit in range(1, 10):
+            bs = threading.BoundedSemaphore(limit)
+            threads = [threading.Thread(target=bs.acquire)
+                       for _ in range(limit)]
+            for t in threads:
+                t.start()
+            for t in threads:
+                t.join()
+            threads = [threading.Thread(target=bs.release)
+                       for _ in range(limit)]
+            for t in threads:
+                t.start()
+            for t in threads:
+                t.join()
+            self.assertRaises(ValueError, bs.release)
+
 class ThreadJoinOnShutdown(BaseTestCase):
 
     def _run_and_join(self, script):
diff --git a/Lib/threading.py b/Lib/threading.py
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -246,7 +246,7 @@
     def __init__(self, value=1):
         if value < 0:
             raise ValueError("semaphore initial value must be >= 0")
-        self._cond = Condition(Lock())
+        self._cond = Condition()
         self._value = value
 
     def acquire(self, blocking=True, timeout=None):
@@ -289,9 +289,10 @@
         self._initial_value = value
 
     def release(self):
-        if self._value >= self._initial_value:
-            raise ValueError("Semaphore released too many times")
-        return Semaphore.release(self)
+        with self._cond:
+            if self._value >= self._initial_value:
+                raise ValueError("Semaphore released too many times")
+            return Semaphore.release(self)
 
 
 class Event: