1 files changed, 2 insertions, 1 deletions
diff --git a/mdoc.c b/mdoc.c
index e51f7771..783ea1a2 100644
--- a/mdoc.c
+++ b/mdoc.c
@@ -241,7 +241,8 @@ mdoc_alloc(void *data, const struct mdoc_cb *cb)
 	p = xcalloc(1, sizeof(struct mdoc));
 
 	p->data = data;
-	(void)memcpy(&p->cb, cb, sizeof(struct mdoc_cb));
+	if (cb)
+		(void)memcpy(&p->cb, cb, sizeof(struct mdoc_cb));
 
 	p->last = xcalloc(1, sizeof(struct mdoc_node));
 	p->last->type = MDOC_ROOT;