diff --git a/tools/mkimage.h b/tools/mkimage.h
index d92a3ff8117..15741f250fd 100644
--- a/tools/mkimage.h
+++ b/tools/mkimage.h
@@ -37,7 +37,7 @@ static inline void *map_sysmem(ulong paddr, unsigned long len)
 	return (void *)(uintptr_t)paddr;
 }
 
-static inline ulong map_to_sysmem(void *ptr)
+static inline ulong map_to_sysmem(const void *ptr)
 {
 	return (ulong)(uintptr_t)ptr;
 }