diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index c9bda6d..fbdfc69 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -299,12 +299,11 @@
 {
 	unsigned long val;
 	int cpu = dev->id;
-	int ret = 0;
-	char *end;
+	ssize_t ret = 0;
 
-	val = simple_strtoul(buf, &end, 0);
-	if (end == buf)
-		return -EINVAL;
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
 
 	if (val == 1) {
 		get_online_cpus();