diff --git a/arch/x86/kernel/entry64.asm b/arch/x86/kernel/entry64.asm
index f70d9f44..ba38163c 100644
--- a/arch/x86/kernel/entry64.asm
+++ b/arch/x86/kernel/entry64.asm
@@ -1146,8 +1146,14 @@ common_switch:
     xor rax, rax
 %endif
     add rax, task_state_segments
-    ; set rsp0 in TSS
-    mov [rax+4], rsp
+
+    ; determine and set esp0 in TSS
+    mov rbx, rsp
+    mov rcx, KERNEL_STACK_SIZE-1
+    not rcx
+    and rbx, rcx
+    add rbx, KERNEL_STACK_SIZE-16
+    mov [rax+4], rbx
 
     ; call cleanup code
     call finish_task_switch