diff --git a/src/lib/core/ssl_impl.c b/src/lib/core/ssl_impl.c
index f1ee092c9f763f87a17209e8ef288ff335f4b32a..38b86b379754f4db8c6e6ed77c42b53c3dc0061e 100644
--- a/src/lib/core/ssl_impl.c
+++ b/src/lib/core/ssl_impl.c
@@ -376,6 +376,9 @@ ssl_iostream_create_supported(struct iostream *io, int fd,
 	io->fd = fd;
 	io->data = ssl;
 	io->vtab = &ssl_iostream_vtab;
+#ifndef NDEBUG
+	io->owner = NULL;
+#endif
 	return 0;
 }