diff --git a/tests/vboot_api_kernel2_tests.c b/tests/vboot_api_kernel2_tests.c
index 2469512..49a4233 100644
--- a/tests/vboot_api_kernel2_tests.c
+++ b/tests/vboot_api_kernel2_tests.c
@@ -157,7 +157,8 @@
 uint32_t VbExKeyboardReadWithFlags(uint32_t *key_flags)
 {
 	if (mock_keypress_count < ARRAY_SIZE(mock_keypress)) {
-		if (key_flags != NULL)
+		if (key_flags != NULL &&
+		    mock_keypress_count < ARRAY_SIZE(mock_keyflags))
 			*key_flags = mock_keyflags[mock_keypress_count];
 		return mock_keypress[mock_keypress_count++];
 	} else