diff --git a/tests/qtest/bios-tables-test.c b/tests/qtest/bios-tables-test.c
index 359916c228..7c5f736b51 100644
--- a/tests/qtest/bios-tables-test.c
+++ b/tests/qtest/bios-tables-test.c
@@ -1632,7 +1632,9 @@ static void test_acpi_q35_applesmc(void)
         .variant = ".applesmc",
     };
 
-    test_acpi_one("-device isa-applesmc", &data);
+    /* supply fake 64-byte OSK to silence missing key warning */
+    test_acpi_one("-device isa-applesmc,osk=any64characterfakeoskisenough"
+                  "topreventinvalidkeywarningsonstderr", &data);
     free_test_data(&data);
 }