diff --git a/infra/stream/InputStream.hpp b/infra/stream/InputStream.hpp
index 467b04ffe..8cf8c1bd5 100644
--- a/infra/stream/InputStream.hpp
+++ b/infra/stream/InputStream.hpp
@@ -19,7 +19,7 @@ namespace infra
         StreamReader() = default;
         StreamReader(const StreamReader& other) = delete;
         StreamReader& operator=(const StreamReader& other) = delete;
-        virtual ~StreamReader() = default;
+        ~StreamReader() = default;
 
     public:
         virtual void Extract(ByteRange range, StreamErrorPolicy& errorPolicy) = 0;
diff --git a/infra/stream/OutputStream.hpp b/infra/stream/OutputStream.hpp
index a0fe2702f..6b77c21cc 100644
--- a/infra/stream/OutputStream.hpp
+++ b/infra/stream/OutputStream.hpp
@@ -21,7 +21,7 @@ namespace infra
         StreamWriter() = default;
         StreamWriter(const StreamWriter&) = delete;
         StreamWriter& operator=(const StreamWriter&) = delete;
-        virtual ~StreamWriter() = default;
+        ~StreamWriter() = default;
 
     public:
         virtual void Insert(ConstByteRange range, StreamErrorPolicy& errorPolicy) = 0;
diff --git a/infra/util/Observer.hpp b/infra/util/Observer.hpp
index 724de13e6..53a62f8f7 100644
--- a/infra/util/Observer.hpp
+++ b/infra/util/Observer.hpp
@@ -26,7 +26,7 @@ namespace infra
     protected:
         Observer(const Observer& other) = delete;
         Observer& operator=(const Observer& other) = delete;
-        virtual ~Observer();
+        ~Observer();
 
     public:
         SubjectType& Subject() const;
@@ -67,7 +67,7 @@ namespace infra
     protected:
         SingleObserver(const SingleObserver& other) = delete;
         SingleObserver& operator=(const SingleObserver& other) = delete;
-        virtual ~SingleObserver();
+        ~SingleObserver();
 
     public:
         SubjectType& Subject() const;
@@ -104,7 +104,7 @@ namespace infra
         Subject() = default;
         Subject(const Subject&) = delete;
         Subject& operator=(const Subject&) = delete;
-        virtual ~Subject();
+        ~Subject();
 
         using SubjectType = typename ObserverType::SubjectType;
         friend class Observer<ObserverType_, SubjectType>;
@@ -136,7 +136,7 @@ namespace infra
         Subject() = default;
         Subject(const Subject&) = delete;
         Subject& operator=(const Subject&) = delete;
-        virtual ~Subject();
+        ~Subject();
 
         friend class SingleObserver<ObserverType_, ObserverSubjectType>;
         virtual void RegisterObserver(SingleObserver<ObserverType_, ObserverSubjectType>* observer);
diff --git a/services/network/ConnectionFactoryWithNameResolver.hpp b/services/network/ConnectionFactoryWithNameResolver.hpp
index 8dc02bfd1..46afd0f99 100644
--- a/services/network/ConnectionFactoryWithNameResolver.hpp
+++ b/services/network/ConnectionFactoryWithNameResolver.hpp
@@ -14,7 +14,7 @@ namespace services
         ClientConnectionObserverFactoryWithNameResolver() = default;
         ClientConnectionObserverFactoryWithNameResolver(const ClientConnectionObserverFactoryWithNameResolver& other) = delete;
         ClientConnectionObserverFactoryWithNameResolver& operator=(const ClientConnectionObserverFactoryWithNameResolver& other) = delete;
-        virtual ~ClientConnectionObserverFactoryWithNameResolver() = default;
+        ~ClientConnectionObserverFactoryWithNameResolver() = default;
 
     public:
         enum ConnectFailReason
@@ -39,7 +39,7 @@ namespace services
         ConnectionFactoryWithNameResolver() = default;
         ConnectionFactoryWithNameResolver(const ConnectionFactoryWithNameResolver& other) = delete;
         ConnectionFactoryWithNameResolver& operator=(const ConnectionFactoryWithNameResolver& other) = delete;
-        virtual ~ConnectionFactoryWithNameResolver() = default;
+        ~ConnectionFactoryWithNameResolver() = default;
 
     public:
         virtual void Connect(ClientConnectionObserverFactoryWithNameResolver& factory) = 0;
diff --git a/services/network/WebSocketClientConnectionObserver.hpp b/services/network/WebSocketClientConnectionObserver.hpp
index 5875fbca8..cfc8214dc 100644
--- a/services/network/WebSocketClientConnectionObserver.hpp
+++ b/services/network/WebSocketClientConnectionObserver.hpp
@@ -20,7 +20,7 @@ namespace services
         WebSocketClientObserverFactory() = default;
         WebSocketClientObserverFactory(const WebSocketClientObserverFactory& other) = delete;
         WebSocketClientObserverFactory& operator=(const WebSocketClientObserverFactory& other) = delete;
-        virtual ~WebSocketClientObserverFactory() = default;
+        ~WebSocketClientObserverFactory() = default;
 
     public:
         enum ConnectFailReason
@@ -44,7 +44,7 @@ namespace services
         WebSocketClientConnector() = default;
         WebSocketClientConnector(const WebSocketClientConnector& other) = delete;
         WebSocketClientConnector& operator=(const WebSocketClientConnector& other) = delete;
-        virtual ~WebSocketClientConnector() = default;
+        ~WebSocketClientConnector() = default;
 
     public:
         virtual void Connect(WebSocketClientObserverFactory& factory) = 0;
@@ -147,7 +147,7 @@ namespace services
         HttpClientWebSocketInitiationResult() = default;
         HttpClientWebSocketInitiationResult(const HttpClientWebSocketInitiationResult& other) = delete;
         HttpClientWebSocketInitiationResult& operator=(const HttpClientWebSocketInitiationResult& other) = delete;
-        virtual ~HttpClientWebSocketInitiationResult() = default;
+        ~HttpClientWebSocketInitiationResult() = default;
 
     public:
         virtual void WebSocketInitiationDone(Connection& connection) = 0;
@@ -195,7 +195,7 @@ namespace services
         WebSocketClientInitiationResult() = default;
         WebSocketClientInitiationResult(const WebSocketClientInitiationResult& other) = delete;
         WebSocketClientInitiationResult& operator=(const WebSocketClientInitiationResult& other) = delete;
-        virtual ~WebSocketClientInitiationResult() = default;
+        ~WebSocketClientInitiationResult() = default;
 
     public:
         virtual void InitiationDone(services::Connection& connection) = 0;