diff --git a/kaneton/machine/architecture/ia32/educational/idt.c b/kaneton/machine/architecture/ia32/educational/idt.c
index 830dc9f..52a78fc 100644
--- a/kaneton/machine/architecture/ia32/educational/idt.c
+++ b/kaneton/machine/architecture/ia32/educational/idt.c
@@ -86,7 +86,7 @@ t_error			architecture_idt_import(void)
 {
   as_idtr lidt;
 
-  lidt.limit = ARCHITECTURE_IDT_SIZE * sizeof (at_idte);
+  lidt.limit = ARCHITECTURE_IDT_SIZE * sizeof (at_idte) - 1;
   lidt.base = (t_paddr) &_idt;
 
   ARCHITECTURE_LIDT(lidt);