diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
index e733ec4..aaf66d4 100644
--- a/arch/arm/cpu/mmu.c
+++ b/arch/arm/cpu/mmu.c
@@ -393,7 +393,7 @@
 	return ret;
 }
 
-unsigned long virt_to_phys(void *virt)
+unsigned long virt_to_phys(volatile void *virt)
 {
 	return (unsigned long)virt;
 }
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h
index 4234979..c6e425f 100644
--- a/arch/arm/include/asm/mmu.h
+++ b/arch/arm/include/asm/mmu.h
@@ -39,7 +39,7 @@
 void dma_clean_range(unsigned long, unsigned long);
 void dma_flush_range(unsigned long, unsigned long);
 void dma_inv_range(unsigned long, unsigned long);
-unsigned long virt_to_phys(void *virt);
+unsigned long virt_to_phys(volatile void *virt);
 void *phys_to_virt(unsigned long phys);
 void remap_range(void *_start, size_t size, uint32_t flags);
 void *map_io_sections(unsigned long physaddr, void *start, size_t size);
@@ -62,7 +62,7 @@
 	return (void *)phys;
 }
 
-static inline unsigned long virt_to_phys(void *mem)
+static inline unsigned long virt_to_phys(volatile void *mem)
 {
 	return (unsigned long)mem;
 }