diff --git a/include/maxscale/users.h b/include/maxscale/users.h
index cf674c8e3..8d5fa69f8 100644
--- a/include/maxscale/users.h
+++ b/include/maxscale/users.h
@@ -115,10 +115,9 @@ int users_default_loadusers(SERV_LISTENER *port);
 /**
  * @brief Default authenticator diagnostic function
  *
- * @param dcb DCB where data is printed
  * @param port Port whose data is to be printed
  */
-void users_default_diagnostic(DCB *dcb, SERV_LISTENER *port);
+json_t* users_default_diagnostic(SERV_LISTENER *port);
 
 /**
  * Print details of the users storage mechanism
diff --git a/server/core/users.cc b/server/core/users.cc
index ae5f5d901..6a119c63d 100644
--- a/server/core/users.cc
+++ b/server/core/users.cc
@@ -109,32 +109,28 @@ void usersPrint(const USERS *users)
     hashtable_stats(users->data);
 }
 
-void users_default_diagnostic(DCB *dcb, SERV_LISTENER *port)
+json_t* users_default_diagnostic(SERV_LISTENER *port)
 {
+    json_t* rval = json_array();
+
     if (port->users && port->users->data)
     {
         HASHITERATOR *iter = hashtable_iterator(port->users->data);
 
         if (iter)
         {
-            dcb_printf(dcb, "User names: ");
-            const char *sep = "";
-            void *user;
+            char* user;
 
-            while ((user = hashtable_next(iter)) != NULL)
+            while ((user = (char*)hashtable_next(iter)))
             {
-                dcb_printf(dcb, "%s%s", sep, (char *)user);
-                sep = ", ";
+                json_array_append(rval, json_string(user));
             }
 
-            dcb_printf(dcb, "\n");
             hashtable_iterator_free(iter);
         }
     }
-    else
-    {
-        dcb_printf(dcb, "Users table is empty\n");
-    }
+
+    return rval;
 }
 
 int users_default_loadusers(SERV_LISTENER *port)
diff --git a/server/modules/authenticator/MySQLAuth/mysql_auth.c b/server/modules/authenticator/MySQLAuth/mysql_auth.c
index 062662fb7..c3ef0f964 100644
--- a/server/modules/authenticator/MySQLAuth/mysql_auth.c
+++ b/server/modules/authenticator/MySQLAuth/mysql_auth.c
@@ -58,7 +58,7 @@ static int mysql_auth_set_client_data(
     MySQLProtocol *protocol,
     GWBUF         *buffer);
 
-void mysql_auth_diagnostic(DCB *dcb, SERV_LISTENER *port);
+json_t* mysql_auth_diagnostic(SERV_LISTENER *port);
 
 int mysql_auth_reauthenticate(DCB *dcb, const char *user,
                               uint8_t *token, size_t token_len,
@@ -682,24 +682,28 @@ int mysql_auth_reauthenticate(DCB *dcb, const char *user,
 
 int diag_cb(void *data, int columns, char **row, char **field_names)
 {
-    DCB *dcb = (DCB*)data;
-    dcb_printf(dcb, "%s@%s ", row[0], row[1]);
+    json_t* obj = json_object();
+    json_object_set_new(obj, "user", json_string(row[0]));
+    json_object_set_new(obj, "host", json_string(row[1]));
+
+    json_t* arr = (json_t*)data;
+    json_array_append(arr, obj);
     return 0;
 }
 
-void mysql_auth_diagnostic(DCB *dcb, SERV_LISTENER *port)
+json_t* mysql_auth_diagnostic(SERV_LISTENER *port)
 {
-    dcb_printf(dcb, "User names: ");
+    json_t* rval = json_array();
 
     MYSQL_AUTH *instance = (MYSQL_AUTH*)port->auth_instance;
     char *err;
 
     if (sqlite3_exec(instance->handle, "SELECT user, host FROM " MYSQLAUTH_USERS_TABLE_NAME,
-                     diag_cb, dcb, &err) != SQLITE_OK)
+                     diag_cb, rval, &err) != SQLITE_OK)
     {
-        dcb_printf(dcb, "Failed to print users: %s\n", err);
         MXS_ERROR("Failed to print users: %s", err);
         sqlite3_free(err);
     }
-    dcb_printf(dcb, "\n");
+
+    return rval;
 }