diff --git a/os/src/boards/qemu.rs b/os/src/boards/qemu.rs
index 0508dfa..87668ba 100644
--- a/os/src/boards/qemu.rs
+++ b/os/src/boards/qemu.rs
@@ -1,5 +1,5 @@
 pub const CLOCK_FREQ: usize = 12500000;
-pub const MEMORY_END: usize = 0x801000000;
+pub const MEMORY_END: usize = 0x88000000;
 
 pub const MMIO: &[(usize, usize)] = &[
     (0x0010_0000, 0x00_2000), // VIRT_TEST/RTC  in virt machine