diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 5e4771266f1a..9b9f18b49918 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -119,7 +119,7 @@ static __init void early_serial_init(char *s)
 	unsigned char c;
 	unsigned divisor;
 	unsigned baud = DEFAULT_BAUD;
-	ssize_t ret;
+	char *e;
 
 	if (*s == ',')
 		++s;
@@ -127,14 +127,14 @@ static __init void early_serial_init(char *s)
 	if (*s) {
 		unsigned port;
 		if (!strncmp(s, "0x", 2)) {
-			ret = kstrtoint(s, 16, &early_serial_base);
+			early_serial_base = simple_strtoul(s, &e, 16);
 		} else {
 			static const int __initconst bases[] = { 0x3f8, 0x2f8 };
 
 			if (!strncmp(s, "ttyS", 4))
 				s += 4;
-			ret = kstrtouint(s, 10, &port);
-			if (ret || port > 1)
+			port = simple_strtoul(s, &e, 10);
+			if (port > 1 || s == e)
 				port = 0;
 			early_serial_base = bases[port];
 		}
@@ -149,8 +149,8 @@ static __init void early_serial_init(char *s)
 	outb(0x3, early_serial_base + MCR);	/* DTR + RTS */
 
 	if (*s) {
-		ret = kstrtouint(s, 0, &baud);
-		if (ret || baud == 0)
+		baud = simple_strtoul(s, &e, 0);
+		if (baud == 0 || s == e)
 			baud = DEFAULT_BAUD;
 	}