diff --git a/Lib/threading.py b/Lib/threading.py
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -324,40 +324,38 @@
             raise ValueError("can't specify timeout for non-blocking acquire")
         rc = False
         endtime = None
-        self._cond.acquire()
-        while self._value == 0:
-            if not blocking:
-                break
-            if __debug__:
-                self._note("%s.acquire(%s): blocked waiting, value=%s",
-                           self, blocking, self._value)
-            if timeout is not None:
-                if endtime is None:
-                    endtime = _time() + timeout
-                else:
-                    timeout = endtime - _time()
-                    if timeout <= 0:
-                        break
-            self._cond.wait(timeout)
-        else:
-            self._value = self._value - 1
-            if __debug__:
-                self._note("%s.acquire: success, value=%s",
-                           self, self._value)
-            rc = True
-        self._cond.release()
+        with self._cond:
+            while self._value == 0:
+                if not blocking:
+                    break
+                if __debug__:
+                    self._note("%s.acquire(%s): blocked waiting, value=%s",
+                            self, blocking, self._value)
+                if timeout is not None:
+                    if endtime is None:
+                        endtime = _time() + timeout
+                    else:
+                        timeout = endtime - _time()
+                        if timeout <= 0:
+                            break
+                self._cond.wait(timeout)
+            else:
+                self._value = self._value - 1
+                if __debug__:
+                    self._note("%s.acquire: success, value=%s",
+                            self, self._value)
+                rc = True
         return rc
 
     __enter__ = acquire
 
     def release(self):
-        self._cond.acquire()
-        self._value = self._value + 1
-        if __debug__:
-            self._note("%s.release: success, value=%s",
-                       self, self._value)
-        self._cond.notify()
-        self._cond.release()
+        with self._cond:
+            self._value = self._value + 1
+            if __debug__:
+                self._note("%s.release: success, value=%s",
+                        self, self._value)
+            self._cond.notify()
 
     def __exit__(self, t, v, tb):
         self.release()
@@ -400,28 +398,19 @@
     isSet = is_set
 
     def set(self):
-        self._cond.acquire()
-        try:
+        with self._cond:
             self._flag = True
             self._cond.notify_all()
-        finally:
-            self._cond.release()
 
     def clear(self):
-        self._cond.acquire()
-        try:
+        with self._cond:
             self._flag = False
-        finally:
-            self._cond.release()
 
     def wait(self, timeout=None):
-        self._cond.acquire()
-        try:
+        with self._cond:
             if not self._flag:
                 self._cond.wait(timeout)
             return self._flag
-        finally:
-            self._cond.release()
 
 
 # A barrier class.  Inspired in part by the pthread_barrier_* api and