diff --git a/include/linux/of.h b/include/linux/of.h
index 4fc4c1b..b238520 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -198,7 +198,7 @@
 extern int of_property_read_u32(struct device_node *np, char *propname,
 					u32 *out_value);
 extern int of_property_read_string(struct device_node *np, char *propname,
-					char **out_string);
+					const char **out_string);
 extern int of_device_is_compatible(const struct device_node *device,
 				   const char *);
 extern int of_device_is_available(const struct device_node *device);