diff --git a/src/input/ReaderBackend.cc b/src/input/ReaderBackend.cc
index ca3d0e1e5f..656743abb5 100644
--- a/src/input/ReaderBackend.cc
+++ b/src/input/ReaderBackend.cc
@@ -9,7 +9,7 @@ using threading::Field;
 
 namespace input {
 
-class PutMessage : public threading::OutputMessage<ReaderFrontend> {
+class PutMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	PutMessage(ReaderFrontend* reader, Value* *val)
 		: threading::OutputMessage<ReaderFrontend>("Put", reader),
@@ -25,7 +25,7 @@ private:
 	Value* *val;
 };
 
-class DeleteMessage : public threading::OutputMessage<ReaderFrontend> {
+class DeleteMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	DeleteMessage(ReaderFrontend* reader, Value* *val)
 		: threading::OutputMessage<ReaderFrontend>("Delete", reader),
@@ -40,7 +40,7 @@ private:
 	Value* *val;
 };
 
-class ClearMessage : public threading::OutputMessage<ReaderFrontend> {
+class ClearMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	ClearMessage(ReaderFrontend* reader)
 		: threading::OutputMessage<ReaderFrontend>("Clear", reader) {}
@@ -54,7 +54,7 @@ public:
 private:
 };
 
-class SendEventMessage : public threading::OutputMessage<ReaderFrontend> {
+class SendEventMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	SendEventMessage(ReaderFrontend* reader, const char* name, const int num_vals, Value* *val)
 		: threading::OutputMessage<ReaderFrontend>("SendEvent", reader),
@@ -78,7 +78,7 @@ private:
 	Value* *val;
 };
 
-class ReaderErrorMessage : public threading::OutputMessage<ReaderFrontend>
+class ReaderErrorMessage final : public threading::OutputMessage<ReaderFrontend>
 {
 public:
 	enum Type {
@@ -98,7 +98,7 @@ private:
 	Type type;
 };
 
-class SendEntryMessage : public threading::OutputMessage<ReaderFrontend> {
+class SendEntryMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	SendEntryMessage(ReaderFrontend* reader, Value* *val)
 		: threading::OutputMessage<ReaderFrontend>("SendEntry", reader),
@@ -114,7 +114,7 @@ private:
 	Value* *val;
 };
 
-class EndCurrentSendMessage : public threading::OutputMessage<ReaderFrontend> {
+class EndCurrentSendMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	EndCurrentSendMessage(ReaderFrontend* reader)
 		: threading::OutputMessage<ReaderFrontend>("EndCurrentSend", reader) {}
@@ -128,7 +128,7 @@ public:
 private:
 };
 
-class EndOfDataMessage : public threading::OutputMessage<ReaderFrontend> {
+class EndOfDataMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	EndOfDataMessage(ReaderFrontend* reader)
 		: threading::OutputMessage<ReaderFrontend>("EndOfData", reader) {}
@@ -142,7 +142,7 @@ public:
 private:
 };
 
-class ReaderClosedMessage : public threading::OutputMessage<ReaderFrontend> {
+class ReaderClosedMessage final : public threading::OutputMessage<ReaderFrontend> {
 public:
 	ReaderClosedMessage(ReaderFrontend* reader)
 		: threading::OutputMessage<ReaderFrontend>("ReaderClosed", reader) {}
@@ -156,7 +156,7 @@ public:
 private:
 };
 
-class DisableMessage : public threading::OutputMessage<ReaderFrontend>
+class DisableMessage final : public threading::OutputMessage<ReaderFrontend>
 {
 public:
 	DisableMessage(ReaderFrontend* writer)
diff --git a/src/input/ReaderFrontend.cc b/src/input/ReaderFrontend.cc
index 8fc44579ab..898d4b30da 100644
--- a/src/input/ReaderFrontend.cc
+++ b/src/input/ReaderFrontend.cc
@@ -6,7 +6,7 @@
 
 namespace input {
 
-class InitMessage : public threading::InputMessage<ReaderBackend>
+class InitMessage final : public threading::InputMessage<ReaderBackend>
 {
 public:
 	InitMessage(ReaderBackend* backend,
@@ -24,7 +24,7 @@ private:
 	const threading::Field* const* fields;
 };
 
-class UpdateMessage : public threading::InputMessage<ReaderBackend>
+class UpdateMessage final : public threading::InputMessage<ReaderBackend>
 {
 public:
 	UpdateMessage(ReaderBackend* backend)
diff --git a/src/logging/WriterBackend.cc b/src/logging/WriterBackend.cc
index 3b055d8bc9..4512234734 100644
--- a/src/logging/WriterBackend.cc
+++ b/src/logging/WriterBackend.cc
@@ -16,7 +16,7 @@ using threading::Field;
 
 namespace logging  {
 
-class RotationFinishedMessage : public threading::OutputMessage<WriterFrontend>
+class RotationFinishedMessage final : public threading::OutputMessage<WriterFrontend>
 {
 public:
 	RotationFinishedMessage(WriterFrontend* writer, const char* new_name, const char* old_name,
@@ -45,7 +45,7 @@ private:
         bool terminating;
 };
 
-class FlushWriteBufferMessage : public threading::OutputMessage<WriterFrontend>
+class FlushWriteBufferMessage final : public threading::OutputMessage<WriterFrontend>
 {
 public:
 	FlushWriteBufferMessage(WriterFrontend* writer)
@@ -54,7 +54,7 @@ public:
 	bool Process() override	{ Object()->FlushWriteBuffer(); return true; }
 };
 
-class DisableMessage : public threading::OutputMessage<WriterFrontend>
+class DisableMessage final : public threading::OutputMessage<WriterFrontend>
 {
 public:
 	DisableMessage(WriterFrontend* writer)
diff --git a/src/logging/WriterFrontend.cc b/src/logging/WriterFrontend.cc
index cb5b171f06..f8ce418482 100644
--- a/src/logging/WriterFrontend.cc
+++ b/src/logging/WriterFrontend.cc
@@ -14,7 +14,7 @@ namespace logging  {
 
 // Messages sent from frontend to backend (i.e., "InputMessages").
 
-class InitMessage : public threading::InputMessage<WriterBackend>
+class InitMessage final : public threading::InputMessage<WriterBackend>
 {
 public:
 	InitMessage(WriterBackend* backend, const int num_fields, const Field* const* fields)
@@ -30,7 +30,7 @@ private:
 	const Field * const* fields;
 };
 
-class RotateMessage : public threading::InputMessage<WriterBackend>
+class RotateMessage final : public threading::InputMessage<WriterBackend>
 {
 public:
 	RotateMessage(WriterBackend* backend, WriterFrontend* frontend, const char* rotated_path, const double open,
@@ -52,7 +52,7 @@ private:
 	const bool terminating;
 };
 
-class WriteMessage : public threading::InputMessage<WriterBackend>
+class WriteMessage final : public threading::InputMessage<WriterBackend>
 {
 public:
 	WriteMessage(WriterBackend* backend, int num_fields, int num_writes, Value*** vals)
@@ -67,7 +67,7 @@ private:
 	Value ***vals;
 };
 
-class SetBufMessage : public threading::InputMessage<WriterBackend>
+class SetBufMessage final : public threading::InputMessage<WriterBackend>
 {
 public:
 	SetBufMessage(WriterBackend* backend, const bool enabled)
@@ -80,7 +80,7 @@ private:
 	const bool enabled;
 };
 
-class FlushMessage : public threading::InputMessage<WriterBackend>
+class FlushMessage final : public threading::InputMessage<WriterBackend>
 {
 public:
 	FlushMessage(WriterBackend* backend, double network_time)
diff --git a/src/threading/MsgThread.cc b/src/threading/MsgThread.cc
index 357d384c96..f662d0a46c 100644
--- a/src/threading/MsgThread.cc
+++ b/src/threading/MsgThread.cc
@@ -15,7 +15,7 @@ namespace threading  {
 ////// Messages.
 
 // Signals child thread to shutdown operation.
-class FinishMessage : public InputMessage<MsgThread>
+class FinishMessage final : public InputMessage<MsgThread>
 {
 public:
 	FinishMessage(MsgThread* thread, double network_time) : InputMessage<MsgThread>("Finish", thread),
@@ -34,7 +34,7 @@ private:
 };
 
 // Signals main thread that operations shut down.
-class FinishedMessage : public OutputMessage<MsgThread>
+class FinishedMessage final : public OutputMessage<MsgThread>
 {
 public:
 	FinishedMessage(MsgThread* thread)
@@ -48,7 +48,7 @@ public:
 };
 
 /// Sends a heartbeat to the child thread.
-class HeartbeatMessage : public InputMessage<MsgThread>
+class HeartbeatMessage final : public InputMessage<MsgThread>
 {
 public:
 	HeartbeatMessage(MsgThread* thread, double arg_network_time, double arg_current_time)
@@ -65,7 +65,7 @@ private:
 };
 
 // A message from the child to be passed on to the Reporter.
-class ReporterMessage : public OutputMessage<MsgThread>
+class ReporterMessage final : public OutputMessage<MsgThread>
 {
 public:
 	enum Type {
@@ -87,7 +87,7 @@ private:
 };
 
 // A message from the the child to the main process, requesting suicide.
-class KillMeMessage : public OutputMessage<MsgThread>
+class KillMeMessage final : public OutputMessage<MsgThread>
 {
 public:
 	KillMeMessage(MsgThread* thread)
@@ -104,7 +104,7 @@ public:
 
 #ifdef DEBUG
 // A debug message from the child to be passed on to the DebugLogger.
-class DebugMessage : public OutputMessage<MsgThread>
+class DebugMessage final : public OutputMessage<MsgThread>
 {
 public:
 	DebugMessage(DebugStream arg_stream, MsgThread* thread, const char* arg_msg)