diff --git a/arch/mips/lantiq/prom.c b/arch/mips/lantiq/prom.c
index 664b7b7222487b03d345b0316f9d240d1ef8b605..cd568921f19117c8ae35912ca2d519782be10b3e 100644
--- a/arch/mips/lantiq/prom.c
+++ b/arch/mips/lantiq/prom.c
@@ -45,10 +45,12 @@ static void __init prom_init_cmdline(void)
 	char **argv = (char **) KSEG1ADDR(fw_arg1);
 	int i;
 
+	arcs_cmdline[0] = '\0';
+
 	for (i = 0; i < argc; i++) {
-		char *p = (char *)  KSEG1ADDR(argv[i]);
+		char *p = (char *) KSEG1ADDR(argv[i]);
 
-		if (p && *p) {
+		if (CPHYSADDR(p) && *p) {
 			strlcat(arcs_cmdline, p, sizeof(arcs_cmdline));
 			strlcat(arcs_cmdline, " ", sizeof(arcs_cmdline));
 		}