diff --git a/board/cm4008/cm4008.c b/board/cm4008/cm4008.c
index d34737c..63296f0 100644
--- a/board/cm4008/cm4008.c
+++ b/board/cm4008/cm4008.c
@@ -46,8 +46,8 @@
  */
 int env_flash_cmdline (void)
 {
-	unsigned char *sp = (unsigned char *) 0x0201c020;
-	unsigned char *ep;
+	char *sp = (char *) 0x0201c020;
+	char *ep;
 	int len;
 
 	/* Check if "erase" push button is depressed */