diff --git a/Documentation/Release-Notes/MaxScale-2.1.7-Release-Notes.md b/Documentation/Release-Notes/MaxScale-2.1.7-Release-Notes.md
index e2b704192..7752de439 100644
--- a/Documentation/Release-Notes/MaxScale-2.1.7-Release-Notes.md
+++ b/Documentation/Release-Notes/MaxScale-2.1.7-Release-Notes.md
@@ -26,6 +26,21 @@ The output of `show servers` now shows the number of times a connection was
 taken from a server's pool as well as the ratio of connections taken from the
 pool versus newly created connections.
 
+### Logging
+
+When known, the session id will be included in all logged messages. This allows
+a range of logged messages related to a particular session (that is, client) to
+be bound together, and makes it easier to investigate problems. In practice this
+is visible so that if a logged message earlier looked like
+```
+2017-08-30 12:20:49   warning: [masking] The rule ...
+```
+it will now look like
+```
+2017-08-30 12:20:49   warning: (4711) [masking] The rule ...
+```
+where `4711` is the session id.
+
 ## Bug fixes
 
 [Here is a list of bugs fixed in MaxScale 2.1.7.](https://jira.mariadb.org/issues/?jql=project%20%3D%20MXS%20AND%20issuetype%20%3D%20Bug%20AND%20status%20%3D%20Closed%20AND%20fixVersion%20%3D%202.1.7)
diff --git a/server/core/log_manager.cc b/server/core/log_manager.cc
index 358d2bc3b..044869c31 100644
--- a/server/core/log_manager.cc
+++ b/server/core/log_manager.cc
@@ -11,25 +11,29 @@
  * Public License.
  */
 #include <maxscale/log_manager.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
 
-#include <unistd.h>
-#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <sched.h>
+#include <stdarg.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <stdarg.h>
-#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 #include <syslog.h>
-#include <maxscale/atomic.h>
-#include <maxscale/platform.h>
+#include <unistd.h>
 
-#include <maxscale/hashtable.h>
-#include <maxscale/spinlock.h>
-#include <maxscale/debug.h>
 #include <maxscale/alloc.h>
+#include <maxscale/atomic.h>
+#include <maxscale/config.h>
+#include <maxscale/debug.h>
+#include <maxscale/hashtable.h>
+#include <maxscale/platform.h>
+#include <maxscale/session.h>
+#include <maxscale/spinlock.h>
 #include <maxscale/utils.h>
 #include "maxscale/mlist.h"
 
@@ -2895,6 +2899,21 @@ int mxs_log_message(int priority,
         {
             va_list valist;
 
+            uint64_t session_id = session_get_current_id();
+            int session_len = 0;
+
+            char session[20]; // Enough to fit "9223372036854775807"
+
+            if (session_id != 0)
+            {
+                sprintf(session, "%" PRIu64, session_id);
+                session_len = strlen(session) + 3; // +3 due to "() "
+            }
+            else
+            {
+                session_len = 0;
+            }
+
             int modname_len = modname ? strlen(modname) + 3 : 0; // +3 due to "[...] "
 
             static const char SUPPRESSION[] =
@@ -2940,6 +2959,7 @@ int mxs_log_message(int priority,
 
                 int buffer_len = 0;
                 buffer_len += prefix.len;
+                buffer_len += session_len;
                 buffer_len += modname_len;
                 buffer_len += augmentation_len;
                 buffer_len += message_len;
@@ -2958,13 +2978,21 @@ int mxs_log_message(int priority,
                 char buffer[buffer_len];
 
                 char *prefix_text = buffer;
-                char *modname_text = prefix_text + prefix.len;
+                char *session_text = prefix_text + prefix.len;
+                char *modname_text = session_text + session_len;
                 char *augmentation_text = modname_text + modname_len;
                 char *message_text = augmentation_text + augmentation_len;
                 char *suppression_text = message_text + message_len;
 
                 strcpy(prefix_text, prefix.text);
 
+                if (session_len)
+                {
+                    strcpy(session_text, "(");
+                    strcat(session_text, session);
+                    strcat(session_text, ") ");
+                }
+
                 if (modname_len)
                 {
                     strcpy(modname_text, "[");