diff --git a/src/ctx.cpp b/src/ctx.cpp
index 024e813a..84f9b037 100644
--- a/src/ctx.cpp
+++ b/src/ctx.cpp
@@ -291,14 +291,22 @@ zmq::endpoint_t zmq::ctx_t::find_endpoint (const char *addr_)
      return *endpoint;
 }
 
-void zmq::ctx_t::log (zmq_msg_t *msg_)
+void zmq::ctx_t::log (const char *format_, va_list args_)
 {
+    //  Create the log message.
+    zmq_msg_t msg;
+    int rc = zmq_msg_init_size (&msg, strlen (format_) + 1);
+    zmq_assert (rc == 0);
+    memcpy (zmq_msg_data (&msg), format_, zmq_msg_size (&msg));
+
     //  At this  point we migrate the log socket to the current thread.
     //  We rely on mutex for executing the memory barrier.
     log_sync.lock ();
     if (log_socket)
-        log_socket->send (msg_, 0);
+        log_socket->send (&msg, 0);
     log_sync.unlock ();
+
+    zmq_msg_close (&msg);
 }
 
 
diff --git a/src/ctx.hpp b/src/ctx.hpp
index c07711e5..04449c40 100644
--- a/src/ctx.hpp
+++ b/src/ctx.hpp
@@ -23,6 +23,7 @@
 #include <map>
 #include <vector>
 #include <string>
+#include <stdarg.h>
 
 #include "../include/zmq.h"
 
@@ -85,7 +86,7 @@ namespace zmq
         endpoint_t find_endpoint (const char *addr_);
 
         //  Logging.
-        void log (zmq_msg_t *msg_);
+        void log (const char *format_, va_list args_);
 
         enum {
             term_tid = 0,
diff --git a/src/object.cpp b/src/object.cpp
index 9ec73f78..1376699a 100644
--- a/src/object.cpp
+++ b/src/object.cpp
@@ -18,6 +18,7 @@
 */
 
 #include <string.h>
+#include <stdarg.h>
 
 #include "object.hpp"
 #include "ctx.hpp"
@@ -151,9 +152,12 @@ void zmq::object_t::destroy_socket (socket_base_t *socket_)
     ctx->destroy_socket (socket_);
 }
 
-void zmq::object_t::log (zmq_msg_t *msg_)
+void zmq::object_t::log (const char *format_, ...)
 {
-    ctx->log (msg_);
+    va_list args;
+    va_start (args, format_);
+    ctx->log (format_, args);
+    va_end (args);
 }
 
 zmq::io_thread_t *zmq::object_t::choose_io_thread (uint64_t affinity_)
diff --git a/src/object.hpp b/src/object.hpp
index 748a339a..af4303ce 100644
--- a/src/object.hpp
+++ b/src/object.hpp
@@ -52,7 +52,7 @@ namespace zmq
         void destroy_socket (class socket_base_t *socket_);
 
         //  Logs an message.
-        void log (zmq_msg_t *msg_);
+        void log (const char *format_, ...);
 
         //  Chooses least loaded I/O thread.
         class io_thread_t *choose_io_thread (uint64_t affinity_);
diff --git a/src/session.cpp b/src/session.cpp
index 350d0435..645ebf06 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -234,6 +234,7 @@ void zmq::session_t::process_attach (i_engine *engine_,
     //  If the session already has an engine attached, destroy new one.
     //  Note new engine is not plugged in yet, we don't have to unplug it.
     if (engine) {
+        log ("DPID: duplicate peer identity - disconnecting peer");
         delete engine_;
         return;
     }