diff --git a/os/src/mm/mod.rs b/os/src/mm/mod.rs
index 350b4fad..b156d255 100644
--- a/os/src/mm/mod.rs
+++ b/os/src/mm/mod.rs
@@ -22,5 +22,5 @@ pub use memory_set::remap_test;
 pub fn init() {
     heap_allocator::init_heap();
     frame_allocator::init_frame_allocator();
-    KERNEL_SPACE.clone().lock().activate();
+    KERNEL_SPACE.lock().activate();
 }