diff --git a/visor.c b/visor.c
index 3bf4951..c5527b1 100644
--- a/visor.c
+++ b/visor.c
@@ -119,7 +119,18 @@ void draw_mandelbrot(struct threadInfo *info)
 			pixmap[4*(i*w + j) + 0] = b;
 		}
 	}
+	pthread_mutex_lock(&pixmapMutex);
 	info->complete = true;
+	bool allWritersComplete = true;
+	for (int32_t i = 0; i < thread_count; i++) {
+		if (!threads[i].complete) {
+			allWritersComplete = false;
+		}
+	}
+	if (allWritersComplete) {
+		cairo_surface_mark_dirty(surface);
+	}
+	pthread_mutex_unlock(&pixmapMutex);
 }
 
 #define MAX_ITERATION 1000