diff --git a/screen-write.c b/screen-write.c
index 3e5128dd..fe74dab3 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -2204,7 +2204,9 @@ screen_write_alternateon(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	screen_write_collect_flush(ctx, 0, __func__);
 	screen_alternate_on(ctx->s, gc, cursor);
-	layout_fix_panes(wp->window, NULL);
+
+	if (wp != NULL)
+		layout_fix_panes(wp->window, NULL);
 
 	screen_write_initctx(ctx, &ttyctx, 1);
 	if (ttyctx.redraw_cb != NULL)
@@ -2224,7 +2226,9 @@ screen_write_alternateoff(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	screen_write_collect_flush(ctx, 0, __func__);
 	screen_alternate_off(ctx->s, gc, cursor);
-	layout_fix_panes(wp->window, NULL);
+
+	if (wp != NULL)
+		layout_fix_panes(wp->window, NULL);
 
 	screen_write_initctx(ctx, &ttyctx, 1);
 	if (ttyctx.redraw_cb != NULL)