diff --git a/lib/io.c b/lib/io.c
index 012a3060a..571ab8e22 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -97,13 +97,17 @@ int io_init(struct io *io, struct format_type *fmt, struct node *n, int flags)
 	io->input.buffer = alloc(io->input.buflen);
 	io->output.buffer = alloc(io->output.buflen);
 
-	if (n) {
-		io->input.node = n;
-		io->output.node = n;
+	io->input.node = n;
+	io->output.node = n;
 
+	if (n) {
 		io->input.signals = &n->signals;
 		io->output.signals = &n->signals;
 	}
+	else {
+		io->input.signals = NULL;
+		io->output.signals = NULL;
+	}
 
 	ret = io->_vt->init ? io->_vt->init(io) : 0;
 	if (ret)
diff --git a/src/test-cmp.c b/src/test-cmp.c
index bd1968e7e..0c5bad66e 100644
--- a/src/test-cmp.c
+++ b/src/test-cmp.c
@@ -130,6 +130,7 @@ check:		if (optarg == endptr)
 	for (int i = 0; i < n; i++) {
 		s[i].format = format;
 		s[i].path = argv[optind + i];
+		s[i].io.state = STATE_DESTROYED;
 
 		s[i].fmt = format_type_lookup(s[i].format);
 		if (!s[i].fmt)