diff --git a/libfprint/drivers/synaptics/usb_transport.c b/libfprint/drivers/synaptics/usb_transport.c
index 0397b77..29e5c10 100644
--- a/libfprint/drivers/synaptics/usb_transport.c
+++ b/libfprint/drivers/synaptics/usb_transport.c
@@ -68,7 +68,8 @@ int usb_check_interrupt(bmkt_usb_transport_t *usb_xport)
 			return (void *)BMKT_GENERAL_ERROR;
 		}
 	}
-	return;
+
+	return BMKT_SUCCESS;
 }
 
 int usb_open(bmkt_usb_transport_t *usb_xport)