From 03c35d2659bc4d66e957b450dc869547f1260642 Mon Sep 17 00:00:00 2001
From: Martin Hurton <hurtonm@gmail.com>
Date: Thu, 23 Oct 2014 10:24:03 +0200
Subject: [PATCH] Fix issue #1224

---
 src/xpub.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/xpub.cpp b/src/xpub.cpp
index 379a4367..7c9bcaea 100644
--- a/src/xpub.cpp
+++ b/src/xpub.cpp
@@ -189,7 +189,8 @@ void zmq::xpub_t::send_unsubscription (unsigned char *data_, size_t size_,
         //  to be retrived by the user later on.
         blob_t unsub (size_ + 1, 0);
         unsub [0] = 0;
-        memcpy (&unsub [1], data_, size_);
+        if (size_ > 0)
+            memcpy (&unsub [1], data_, size_);
         self->pending_data.push_back (unsub);
         self->pending_flags.push_back (0);
     }