diff --git a/libevdev/libevdev-int.h b/libevdev/libevdev-int.h
index 2be555d..61c2454 100644
--- a/libevdev/libevdev-int.h
+++ b/libevdev/libevdev-int.h
@@ -99,7 +99,7 @@ struct libevdev {
 	int rep_values[REP_CNT];
 
 	enum SyncState sync_state;
-	int grabbed;
+	enum libevdev_grab_mode grabbed;
 
 	struct input_event *queue;
 	size_t queue_size; /**< size of queue in elements */
diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index 598455e..95d041c 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -936,7 +936,7 @@ libevdev_set_slot_value(struct libevdev *dev, unsigned int slot, unsigned int co
 	if (!libevdev_has_event_type(dev, EV_ABS) || !libevdev_has_event_code(dev, EV_ABS, code))
 		return -1;
 
-	if (slot >= dev->num_slots || slot >= MAX_SLOTS)
+	if (dev->num_slots == -1 || slot >= (unsigned int)dev->num_slots || slot >= MAX_SLOTS)
 		return -1;
 
 	if (code > ABS_MT_MAX || code < ABS_MT_MIN)