diff --git a/src/control.c b/src/control.c
index 064e0f3..870c8ca 100644
--- a/src/control.c
+++ b/src/control.c
@@ -136,6 +136,9 @@ void trial_wait_for_input(trial *t) {
 	if (len < 0) {
 		fprintf(stderr, "read error: %s\n", strerror(errno));
 		exit(127);
+	} else if (len == 0) {
+		fprintf(stderr, "connection closed\n");
+		exit(125);
 	}
 	g_string_append_len(t->parse_ctx->buffer, buffer, len);
 	control_parse(t);