diff --git a/dlib/iosockstream/iosockstream.h b/dlib/iosockstream/iosockstream.h
index e8b1a68ff..c9c51ac0b 100644
--- a/dlib/iosockstream/iosockstream.h
+++ b/dlib/iosockstream/iosockstream.h
@@ -59,6 +59,7 @@ namespace dlib
             const network_address& addr
         )
         {
+            auto_mutex lock(class_mutex);
             close();
             con.reset(connect(addr));
             buf.reset(new sockstreambuf(con.get()));
@@ -79,6 +80,7 @@ namespace dlib
             unsigned long timeout
         )
         {
+            auto_mutex lock(class_mutex);
             close(timeout);
             con.reset(connect(addr.host_address, addr.port, timeout));
             buf.reset(new sockstreambuf(con.get()));
@@ -91,6 +93,7 @@ namespace dlib
             unsigned long timeout = 10000
         )
         {
+            auto_mutex lock(class_mutex);
             rdbuf(0);
             try
             {
@@ -126,12 +129,21 @@ namespace dlib
             unsigned long timeout
         )
         {
+            auto_mutex lock(class_mutex);
             if (con)
             {
                 con_timeout.reset(new dlib::timeout(*this,&iosockstream::terminate_connection,timeout,con));
             }
         }
 
+        void shutdown (
+        ) 
+        {
+            auto_mutex lock(class_mutex);
+            if (con)
+                con->shutdown();
+        }
+
     private:
 
         void terminate_connection(
@@ -142,6 +154,7 @@ namespace dlib
         }
 
         scoped_ptr<timeout> con_timeout;
+        rmutex class_mutex; 
         shared_ptr_thread_safe<connection> con;
         scoped_ptr<sockstreambuf> buf;
 
diff --git a/dlib/iosockstream/iosockstream_abstract.h b/dlib/iosockstream/iosockstream_abstract.h
index d5ff61e8a..2328f426e 100644
--- a/dlib/iosockstream/iosockstream_abstract.h
+++ b/dlib/iosockstream/iosockstream_abstract.h
@@ -22,8 +22,10 @@ namespace dlib
                 stream's output buffers.  
 
             THREAD SAFETY
-                It is not safe to touch this object from more than one thread at a time.
-                Therefore, you should mutex lock it if you need to do so.  
+                It is not safe for multiple threads to make concurrent accesses to the same
+                instance of this object (except for calls to shutdown() which are always
+                threadsafe).  Therefore, you should mutex lock an instance of this object
+                if you need to touch it from multiple threads. 
         !*/
 
     public:
@@ -147,6 +149,15 @@ namespace dlib
                     - This function has no effect on this object.
         !*/
 
+        void shutdown (
+        );
+        /*!
+            ensures
+                - Immediately closes the TCP connection and causes all I/O operations on
+                  this object to return an error.  
+                - It is safe to call this function from any thread, therefore, you can use
+                  it to signal when you want a connection to terminate from another thread.
+        !*/
     };
 
 // ----------------------------------------------------------------------------------------