diff --git a/common/cmd_diag.c b/common/cmd_diag.c
index 0436c49..317ea66 100644
--- a/common/cmd_diag.c
+++ b/common/cmd_diag.c
@@ -28,7 +28,7 @@
 #include <command.h>
 #include <post.h>
 
-int do_diag (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_diag (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned int i;