diff --git a/libcpu/arm/cortex-r4/interrupt.c b/libcpu/arm/cortex-r4/interrupt.c
index 8d0a977db9b3915ebf375074594292c675579e6e..d001b509ee368129857a05341bd05ad7535f4dca 100644
--- a/libcpu/arm/cortex-r4/interrupt.c
+++ b/libcpu/arm/cortex-r4/interrupt.c
@@ -22,7 +22,7 @@
 /* exception and interrupt handler table */
 struct rt_irq_desc irq_desc[MAX_HANDLERS];
 
-extern rt_uint32_t rt_interrupt_nest;
+extern volatile rt_uint8_t rt_interrupt_nest;
 
 /* exception and interrupt handler table */
 rt_uint32_t rt_interrupt_from_thread, rt_interrupt_to_thread;