diff --git a/sway/desktop/render.c b/sway/desktop/render.c
index b9de2025..47449bb6 100644
--- a/sway/desktop/render.c
+++ b/sway/desktop/render.c
@@ -441,7 +441,7 @@ static void render_surface_iterator(struct sway_output *output,
 		pixman_region32_init(&opaque_region);
 
 		bool has_alpha = false;
-		if (deco_data.alpha < 1.0) {
+		if (deco_data.alpha < 1.0 || deco_data.dim_color[3] < 1.0) {
 			has_alpha = true;
 			pixman_region32_union_rect(&opaque_region, &opaque_region, 0, 0, 0, 0);
 		} else {