diff --git a/arch/x86/mm/memtest.c b/arch/x86/mm/memtest.c
index 0bcd788..605c8be 100644
--- a/arch/x86/mm/memtest.c
+++ b/arch/x86/mm/memtest.c
@@ -100,6 +100,9 @@
 {
 	if (arg)
 		memtest_pattern = simple_strtoul(arg, NULL, 0);
+	else
+		memtest_pattern = ARRAY_SIZE(patterns);
+
 	return 0;
 }