diff --git a/src/compositor-wayland.c b/src/compositor-wayland.c
index 386f9b6..00ad189 100644
--- a/src/compositor-wayland.c
+++ b/src/compositor-wayland.c
@@ -442,6 +442,7 @@
 	output->base.repaint = wayland_output_repaint;
 	output->base.set_hardware_cursor = wayland_output_set_cursor;
 	output->base.destroy = wayland_output_destroy;
+	output->base.assign_planes = NULL;
 
 	wl_list_insert(c->base.output_list.prev, &output->base.link);