diff --git a/include/fdt_support.h b/include/fdt_support.h
index c7b4605..cef3c65 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -28,8 +28,8 @@
 
 #include <fdt.h>
 
-u32 fdt_getprop_u32_default(void *fdt, const char *path, const char *prop,
-				const u32 dflt);
+u32 fdt_getprop_u32_default(const void *fdt, const char *path,
+				const char *prop, const u32 dflt);
 int fdt_chosen(void *fdt, int force);
 int fdt_initrd(void *fdt, ulong initrd_start, ulong initrd_end, int force);
 void do_fixup_by_path(void *fdt, const char *path, const char *prop,