diff --git a/kernel/intr/intr0.S b/kernel/intr/intr0.S
index 9370e05..72f42cc 100644
--- a/kernel/intr/intr0.S
+++ b/kernel/intr/intr0.S
@@ -66,7 +66,9 @@
   _push_regs
   cld
   movq %rsp, %rdi
+  sub $0x8, %rsp
   call intr_handleintr
+  add $0x8, %rsp
   _pop_regs
   add $0x10, %rsp
   iretq
diff --git a/kernel/proc/switch.S b/kernel/proc/switch.S
index d877ce1..4ed3afb 100644
--- a/kernel/proc/switch.S
+++ b/kernel/proc/switch.S
@@ -2,10 +2,7 @@
 
 .global proc_switch
 proc_switch:
-  testq %rsi, %rsi
-  je 1f
   movq %rsi, %cr3
-1:
   mov %rdi, %rsp
   _pop_regs
   add $0x10, %rsp
diff --git a/ulib/_start.S b/ulib/_start.S
index 2a214d8..8a368b7 100644
--- a/ulib/_start.S
+++ b/ulib/_start.S
@@ -4,4 +4,9 @@
 
 .global _start
 _start:
+  xor %rbp, %rbp
+  mov %rsp, %rbp
+  and $-0x10, %rsp
+  sub $0x8, %rsp
+
   call _premain