diff --git a/kernel/src/holeybytes/mod.rs b/kernel/src/holeybytes/mod.rs
index cbf56f7..a7440b4 100644
--- a/kernel/src/holeybytes/mod.rs
+++ b/kernel/src/holeybytes/mod.rs
@@ -21,7 +21,7 @@ type Vm = hbvm::Vm<mem::Memory, TIMER_QUOTIENT>;
 
 pub struct ExecThread<'p> {
     vm: Vm,
-    stack_top: *mut u8,
+    stack_bottom: *mut u8,
     _phantom: PhantomData<&'p [u8]>,
 }
 
@@ -40,12 +40,12 @@ impl<'p> ExecThread<'p> {
             )
         };
 
-        let stack_top = unsafe { allocate_stack().as_ptr().add(STACK_SIZE - 1) };
-        vm.write_reg(254, stack_top as u64);
+        let stack_bottom = unsafe { allocate_stack().as_ptr() };
+        vm.write_reg(254, (stack_bottom as usize + STACK_SIZE - 1) as u64);
 
         ExecThread {
             vm,
-            stack_top,
+            stack_bottom,
             _phantom: Default::default(),
         }
     }
@@ -53,7 +53,7 @@ impl<'p> ExecThread<'p> {
 
 impl<'p> Drop for ExecThread<'p> {
     fn drop(&mut self) {
-        unsafe { alloc::alloc::dealloc(self.stack_top.sub(STACK_SIZE - 1), stack_layout()) };
+        unsafe { alloc::alloc::dealloc(self.stack_bottom, stack_layout()) };
     }
 }