diff --git a/tooz/drivers/memcached.py b/tooz/drivers/memcached.py
index 1cefd954..6dacd77f 100644
--- a/tooz/drivers/memcached.py
+++ b/tooz/drivers/memcached.py
@@ -152,10 +152,24 @@ class MemcachedLock(locking.Lock):
         if value != self.coord._member_id:
             return False
         else:
-            was_deleted = self.coord.client.delete(self.name, noreply=False)
-            if was_deleted:
+            # NOTE(zhen): Whether 'was_deleted' was 'TRUE' or not,
+            # eventually we have to remove self from '_acquired_locks'.
+            #
+            # For example:
+            # 1. App #1 with coordinator 'A' wants to release lock "b"
+            # 2. 'self.coord.client.delete()' failed for some reason(.e.g,
+            # BrokenPipeError,MemcacheUnexpectedCloseError)
+            # 3. According to the former logic,lock "b" will not remove
+            # from "_acquired_locks", so "self.heartbeat()" will make it alive
+            # forever until App #1 was down or lock "b" turned expired.
+            # 4. Now App #1 with coordinator 'A' wants to acquire lock "c", who
+            # have the same lock-name with lock "b",It is clear that this will
+            # fail and prevent the locked program from continuing to execute.
+            try:
+                was_deleted = self.coord.client.delete(self.name, noreply=False)
+            finally:
                 self.coord._acquired_locks.remove(self)
-            return was_deleted
+                return was_deleted
 
     @_translate_failures
     def heartbeat(self):