diff --git a/YYCache/YYMemoryCache.m b/YYCache/YYMemoryCache.m
index 9042d9b..3a27ccc 100644
--- a/YYCache/YYMemoryCache.m
+++ b/YYCache/YYMemoryCache.m
@@ -402,8 +402,9 @@ - (id)objectForKey:(id)key {
         node->_time = CACurrentMediaTime();
         [_lru bringNodeToHead:node];
     }
+    id value = node ? node->_value : nil;
     pthread_mutex_unlock(&_lock);
-    return node ? node->_value : nil;
+    return value;
 }
 
 - (void)setObject:(id)object forKey:(id)key {