diff --git a/backend/drm/atomic.c b/backend/drm/atomic.c
index acc56e65..41b6424c 100644
--- a/backend/drm/atomic.c
+++ b/backend/drm/atomic.c
@@ -83,8 +83,8 @@ static void set_plane_props(struct atomic *atom, struct wlr_drm_plane *plane,
 	// The src_* properties are in 16.16 fixed point
 	atomic_add(atom, id, props->src_x, 0);
 	atomic_add(atom, id, props->src_y, 0);
-	atomic_add(atom, id, props->src_w, plane->surf.width << 16);
-	atomic_add(atom, id, props->src_h, plane->surf.height << 16);
+	atomic_add(atom, id, props->src_w, (uint64_t)plane->surf.width << 16);
+	atomic_add(atom, id, props->src_h, (uint64_t)plane->surf.height << 16);
 	atomic_add(atom, id, props->crtc_w, plane->surf.width);
 	atomic_add(atom, id, props->crtc_h, plane->surf.height);
 	atomic_add(atom, id, props->fb_id, fb_id);
diff --git a/backend/drm/drm.c b/backend/drm/drm.c
index c5db480e..f4a971a2 100644
--- a/backend/drm/drm.c
+++ b/backend/drm/drm.c
@@ -973,7 +973,7 @@ int handle_drm_event(int fd, uint32_t mask, void *data) {
 }
 
 void restore_drm_outputs(struct wlr_drm_backend *drm) {
-	uint64_t to_close = (1 << wl_list_length(&drm->outputs)) - 1;
+	uint64_t to_close = (1L << wl_list_length(&drm->outputs)) - 1;
 
 	struct wlr_drm_connector *conn;
 	wl_list_for_each(conn, &drm->outputs, link) {