1 files changed, 1 insertions, 1 deletions
diff --git a/libxo/xo_buf.h b/libxo/xo_buf.h
index 3bb5628a6ea0..d6a05005cd23 100644
--- a/libxo/xo_buf.h
+++ b/libxo/xo_buf.h
@@ -133,7 +133,7 @@ xo_buf_has_room (xo_buffer_t *xbp, ssize_t len)
 static inline void
 xo_buf_append (xo_buffer_t *xbp, const char *str, ssize_t len)
 {
-    if (!xo_buf_has_room(xbp, len))
+    if (str == NULL || len == 0 || !xo_buf_has_room(xbp, len))
 	return;
 
     memcpy(xbp->xb_curp, str, len);