diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index ba5c05e..960a8d9 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -594,19 +594,21 @@
 		/* Some systems map "vectors" to interrupts weirdly.  Lguest has
 		 * a straightforward 1 to 1 mapping, so force that here. */
 		__get_cpu_var(vector_irq)[vector] = i;
-		if (vector != SYSCALL_VECTOR) {
-			set_intr_gate(vector,
-				      interrupt[vector-FIRST_EXTERNAL_VECTOR]);
-			set_irq_chip_and_handler_name(i, &lguest_irq_controller,
-						      handle_level_irq,
-						      "level");
-		}
+		if (vector != SYSCALL_VECTOR)
+			set_intr_gate(vector, interrupt[i]);
 	}
 	/* This call is required to set up for 4k stacks, where we have
 	 * separate stacks for hard and soft interrupts. */
 	irq_ctx_init(smp_processor_id());
 }
 
+void lguest_setup_irq(unsigned int irq)
+{
+	irq_to_desc_alloc_cpu(irq, 0);
+	set_irq_chip_and_handler_name(irq, &lguest_irq_controller,
+				      handle_level_irq, "level");
+}
+
 /*
  * Time.
  *