diff --git a/cpp/src/Ice/SSL/SchannelTransceiverI.h b/cpp/src/Ice/SSL/SchannelTransceiverI.h
index 637c442dbaf..16f0a1cd964 100644
--- a/cpp/src/Ice/SSL/SchannelTransceiverI.h
+++ b/cpp/src/Ice/SSL/SchannelTransceiverI.h
@@ -52,13 +52,13 @@ namespace Ice::SSL::Schannel
         void setBufferSize(int rcvSize, int sndSize) final;
 
     private:
-        IceInternal::SocketOperation sslHandshake(SecBuffer* initialBuffer = nullptr);
+        [[nodiscard]] IceInternal::SocketOperation sslHandshake(SecBuffer* initialBuffer = nullptr);
 
-        size_t decryptMessage(IceInternal::Buffer&);
-        size_t encryptMessage(IceInternal::Buffer&);
+        [[nodiscard]] size_t decryptMessage(IceInternal::Buffer&);
+        [[nodiscard]] size_t encryptMessage(IceInternal::Buffer&);
 
-        bool writeRaw(IceInternal::Buffer&);
-        bool readRaw(IceInternal::Buffer&);
+        [[nodiscard]] bool writeRaw(IceInternal::Buffer&);
+        [[nodiscard]] bool readRaw(IceInternal::Buffer&);
 
         enum State
         {
diff --git a/cpp/src/Ice/SSL/SecureTransportTransceiverI.h b/cpp/src/Ice/SSL/SecureTransportTransceiverI.h
index 7fd2da38e03..d7c248ac12b 100644
--- a/cpp/src/Ice/SSL/SecureTransportTransceiverI.h
+++ b/cpp/src/Ice/SSL/SecureTransportTransceiverI.h
@@ -36,13 +36,14 @@ namespace Ice::SSL::SecureTransport
             const std::string&,
             const Ice::SSL::ClientAuthenticationOptions&);
         ~TransceiverI();
-        IceInternal::NativeInfoPtr getNativeInfo() final;
 
-        IceInternal::SocketOperation initialize(IceInternal::Buffer&, IceInternal::Buffer&) final;
-        IceInternal::SocketOperation closing(bool, std::exception_ptr) final;
+        [[nodiscard]] IceInternal::NativeInfoPtr getNativeInfo() final;
+
+        [[nodiscard]] IceInternal::SocketOperation initialize(IceInternal::Buffer&, IceInternal::Buffer&) final;
+        [[nodiscard]] IceInternal::SocketOperation closing(bool, std::exception_ptr) final;
         void close() final;
-        IceInternal::SocketOperation write(IceInternal::Buffer&) final;
-        IceInternal::SocketOperation read(IceInternal::Buffer&) final;
+        [[nodiscard]] IceInternal::SocketOperation write(IceInternal::Buffer&) final;
+        [[nodiscard]] IceInternal::SocketOperation read(IceInternal::Buffer&) final;
 
         [[nodiscard]] std::string protocol() const final;
         [[nodiscard]] std::string toString() const final;