diff --git a/include/asm-generic/logic_io.h b/include/asm-generic/logic_io.h
index a53116b..8a59b6e 100644
--- a/include/asm-generic/logic_io.h
+++ b/include/asm-generic/logic_io.h
@@ -34,7 +34,7 @@
 void __iomem *ioremap(phys_addr_t offset, size_t size);
 
 #define iounmap iounmap
-void iounmap(void __iomem *addr);
+void iounmap(void volatile __iomem *addr);
 
 #define __raw_readb __raw_readb
 u8 __raw_readb(const volatile void __iomem *addr);
diff --git a/lib/logic_iomem.c b/lib/logic_iomem.c
index 549b22d..8c3365f 100644
--- a/lib/logic_iomem.c
+++ b/lib/logic_iomem.c
@@ -76,7 +76,7 @@ static void __iomem *real_ioremap(phys_addr_t offset, size_t size)
 	return NULL;
 }
 
-static void real_iounmap(void __iomem *addr)
+static void real_iounmap(volatile void __iomem *addr)
 {
 	WARN(1, "invalid iounmap for addr 0x%llx\n",
 	     (unsigned long long)(uintptr_t __force)addr);
@@ -149,7 +149,7 @@ get_area(const volatile void __iomem *addr)
 	return NULL;
 }
 
-void iounmap(void __iomem *addr)
+void iounmap(volatile void __iomem *addr)
 {
 	struct logic_iomem_area *area = get_area(addr);