diff --git a/testsuite/gpiotest/gpiotest.c b/testsuite/gpiotest/gpiotest.c
index 7347ac50660e48252888f0019bb77adba1a7831a..2e4b1bf4d1a5b3b795673a047de2ed42f05583c3 100644
--- a/testsuite/gpiotest/gpiotest.c
+++ b/testsuite/gpiotest/gpiotest.c
@@ -35,6 +35,7 @@ smokey_test_plugin(interrupt,
 			   SMOKEY_STRING(device),
 			   SMOKEY_STRING(trigger),
 			   SMOKEY_BOOL(select),
+			   SMOKEY_BOOL(timestamp),
 		   ),
    "Wait for interrupts from a GPIO pin.\n"
    "\tdevice=<device-path>\n"