diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index ccebf6279c05bd9ee227b9f18e601933f59bd7a3..b0b73f2edfc9bff734d915b903a01eab165ffba9 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -719,7 +719,7 @@ struct radeon_doorbell {
 	resource_size_t		size;
 	u32 __iomem		*ptr;
 	u32			num_doorbells;	/* Number of doorbells actually reserved for radeon. */
-	unsigned long		used[DIV_ROUND_UP(RADEON_MAX_DOORBELLS, BITS_PER_LONG)];
+	DECLARE_BITMAP(used, RADEON_MAX_DOORBELLS);
 };
 
 int radeon_doorbell_get(struct radeon_device *rdev, u32 *page);