diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0404787c..d3b82cfd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -175,6 +175,7 @@ set (wsjt_qt_CXXSRCS
   DXLabSuiteCommanderTransceiver.cpp
   NetworkMessage.cpp
   Message.cpp
+  MessageError.cpp
   MessageClient.cpp
   MessageServer.cpp
   TCPClient.cpp
diff --git a/MessageClient.cpp b/MessageClient.cpp
index ba3cc2d4..66971009 100644
--- a/MessageClient.cpp
+++ b/MessageClient.cpp
@@ -10,6 +10,7 @@
 #include <QUdpSocket>
 
 #include "DriftingDateTime.h"
+#include "MessageError.hpp"
 #include "pimpl_impl.hpp"
 #include "moc_MessageClient.cpp"
 
@@ -28,14 +29,15 @@ namespace
 
 namespace
 {
-  // Exception thrown on JSON parsing errors.
+  // Exception thrown on message parsing errors.
 
-  struct parse_error : public std::runtime_error
+  struct parse_error : public std::system_error
   {
-    explicit parse_error(QString const & what)
-    : std::runtime_error(QString {"json parse error: %1"}
-                                 .arg(what)
-                                 .toStdString())
+    using std::system_error::system_error;
+
+    explicit parse_error(QJsonParseError const & parse)
+    : parse_error(MessageError::Code::json_parsing_error,
+                  parse.errorString().toStdString())
     {}
   };
 
@@ -45,11 +47,13 @@ namespace
   Message
   parse_message(QByteArray const & datagram)
   {
+    using MessageError::Code;
+
     QJsonParseError parse;
     QJsonDocument   document = QJsonDocument::fromJson(datagram, &parse);
 
-    if (parse.error)          throw parse_error(parse.errorString());
-    if (!document.isObject()) throw parse_error("json is not an object");
+    if (parse.error)          throw parse_error(parse);
+    if (!document.isObject()) throw parse_error(Code::json_not_an_object);
 
     Message message;
 
diff --git a/MessageError.cpp b/MessageError.cpp
new file mode 100644
index 00000000..d316f3d2
--- /dev/null
+++ b/MessageError.cpp
@@ -0,0 +1,51 @@
+#include "MessageError.hpp"
+
+/******************************************************************************/
+// Private Implementation
+/******************************************************************************/
+
+#pragma mark Private Implementation
+
+namespace
+{
+    const struct final : public std::error_category
+    {
+        const char *
+        name() const noexcept override
+        {
+            return "message";
+        }
+        
+        std::string
+        message(int const ev) const override
+        {
+            using MessageError::Code;
+            
+            switch (static_cast<Code>(ev))
+            {
+                case Code::json_parsing_error: return "json parsing error";
+                case Code::json_not_an_object: return "json not an object";
+            
+                default: return "message error";
+            }
+        }
+    }
+    Category;
+}
+
+/******************************************************************************/
+// Private Implementation
+/******************************************************************************/
+
+#pragma mark - Implementation
+
+namespace MessageError
+{
+    std::error_category const &
+    category() noexcept
+    {
+        return Category;
+    }
+}
+
+/******************************************************************************/
diff --git a/MessageError.hpp b/MessageError.hpp
new file mode 100644
index 00000000..8c6a45f5
--- /dev/null
+++ b/MessageError.hpp
@@ -0,0 +1,41 @@
+#ifndef MESSAGE_ERROR_HPP__
+#define MESSAGE_ERROR_HPP__
+
+#include <system_error>
+
+namespace MessageError
+{
+    enum class Code
+    {
+        json_parsing_error = -1001,
+        json_not_an_object = -1002
+    };
+
+    std::error_category const & category() noexcept;
+}
+
+namespace std
+{
+    template<>
+    struct is_error_code_enum<MessageError::Code> : public true_type{};
+
+    template<>
+    struct is_error_condition_enum<MessageError::Code> : public true_type{};
+}
+
+namespace MessageError
+{
+    inline std::error_code
+    make_error_code(Code const e) noexcept
+    {
+        return {static_cast<int>(e), category()};
+    }
+
+    inline std::error_condition
+    make_error_condition(Code const e) noexcept
+    {
+        return {static_cast<int>(e), category()};
+    }
+}
+
+#endif