diff --git a/arch/arc/include/asm/io.h b/arch/arc/include/asm/io.h
index 2f39d9b3886e..19d0cab60a39 100644
--- a/arch/arc/include/asm/io.h
+++ b/arch/arc/include/asm/io.h
@@ -35,7 +35,7 @@ static inline void ioport_unmap(void __iomem *addr)
 {
 }
 
-extern void iounmap(const void __iomem *addr);
+extern void iounmap(const volatile void __iomem *addr);
 
 #define ioremap_nocache(phy, sz)	ioremap(phy, sz)
 #define ioremap_wc(phy, sz)		ioremap(phy, sz)
diff --git a/arch/arc/mm/ioremap.c b/arch/arc/mm/ioremap.c
index 9881bd740ccc..0719b1280ef8 100644
--- a/arch/arc/mm/ioremap.c
+++ b/arch/arc/mm/ioremap.c
@@ -95,7 +95,7 @@ void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
 EXPORT_SYMBOL(ioremap_prot);
 
 
-void iounmap(const void __iomem *addr)
+void iounmap(const volatile void __iomem *addr)
 {
 	/* weird double cast to handle phys_addr_t > 32 bits */
 	if (arc_uncached_addr_space((phys_addr_t)(u32)addr))