diff --git a/kernel/heap.asm b/kernel/heap.asm
index a25cdf6..aa774b6 100644
--- a/kernel/heap.asm
+++ b/kernel/heap.asm
@@ -5,10 +5,14 @@ heap_init:
   push ax ; byte value (0)
   push cx ; loop counter
   push di ; target ptr
+  push es
+  mov ax, ds
+  mov es, ax
   xor ax, ax
   mov cx, [heap_size]
   mov di, heap
   rep stosb ; rep makes this loop cx times, incrementing di, writing al
+  pop es
   pop di
   pop cx
   pop ax