diff --git a/src/kernel/thread_manager.rs b/src/kernel/thread_manager.rs
index b7ae47d..962b3f4 100644
--- a/src/kernel/thread_manager.rs
+++ b/src/kernel/thread_manager.rs
@@ -373,6 +373,7 @@ impl ThreadManager {
                 }
             }
         };
+        self.get_obj_addrs().update_lock(id, lock);
         machine.interrupt.set_status(old_status);
         Ok(MachineOk::Ok)
     }
@@ -464,7 +465,7 @@ mod test {
         {
             let lock = thread_manager.get_obj_addrs().search_lock(lock_id).unwrap();
             assert_eq!(lock.owner, None);
-            assert!(!lock.free);
+            assert!(lock.free);
             assert!(lock.waiting_queue.is_empty());
         }
     }
diff --git a/src/utility/objaddr.rs b/src/utility/objaddr.rs
index e788eb0..42ad0a5 100644
--- a/src/utility/objaddr.rs
+++ b/src/utility/objaddr.rs
@@ -66,6 +66,11 @@ impl ObjAddr {
         self.locks.get_mut(&id)
     }
 
+    /// Update lock at given id
+    pub fn update_lock(&mut self, id: i32, lock: Lock) {
+        self.locks.insert(id, lock);
+    }
+
     /// Searches for a lock of id **id** in self
     pub fn search_thread(&mut self, id: i32) -> Option<&Rc<RefCell<Thread>>> {
         self.threads.get(&id)