diff --git a/screen-write.c b/screen-write.c
index 9d710397..894da4b7 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -390,6 +390,8 @@ screen_write_initctx(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx)
 {
 	struct screen	*s = ctx->s;
 
+	memset(ttyctx, 0, sizeof *ttyctx);
+
 	ttyctx->wp = ctx->wp;
 
 	ttyctx->ocx = s->cx;