Index: uspace/drv/usbhid/main.c
===================================================================
--- uspace/drv/usbhid/main.c	(revision e7df6cdbc8c33c666a61830f110b7a40e19aef16)
+++ uspace/drv/usbhid/main.c	(revision 56f8a04e9aa9e71b0207654a6a33d8650333226f)
@@ -74,4 +74,6 @@
 static int usb_hid_try_add_device(usb_device_t *dev)
 {
+	assert(dev != NULL);
+	
 	/* 
 	 * Initialize device (get and process descriptors, get address, etc.)
@@ -177,4 +179,9 @@
 	usb_log_debug("usb_hid_add_device()\n");
 	
+	if (dev != NULL) {
+		usb_log_warning("Wrong parameter given for add_device().\n");
+		return EINVAL;
+	}
+	
 	if (dev->interface_no < 0) {
 		usb_log_warning("Device is not a supported HID device.\n");