diff --git a/src/net.cpp b/src/net.cpp
index c2e45898e80..cf0c9aef7ba 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -797,7 +797,8 @@ CNetMessage V1TransportDeserializer::GetMessage(const std::chrono::microseconds
     return msg;
 }
 
-void V1TransportSerializer::prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) {
+void V1TransportSerializer::prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) const
+{
     // create dbl-sha256 checksum
     uint256 hash = Hash(msg.data);
 
diff --git a/src/net.h b/src/net.h
index 064c448264c..97389314b2b 100644
--- a/src/net.h
+++ b/src/net.h
@@ -325,13 +325,13 @@ public:
 class TransportSerializer {
 public:
     // prepare message for transport (header construction, error-correction computation, payload encryption, etc.)
-    virtual void prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) = 0;
+    virtual void prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) const = 0;
     virtual ~TransportSerializer() {}
 };
 
-class V1TransportSerializer  : public TransportSerializer {
+class V1TransportSerializer : public TransportSerializer {
 public:
-    void prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) override;
+    void prepareForTransport(CSerializedNetMsg& msg, std::vector<unsigned char>& header) const override;
 };
 
 /** Information about a peer */
@@ -342,7 +342,7 @@ class CNode
 
 public:
     std::unique_ptr<TransportDeserializer> m_deserializer;
-    std::unique_ptr<TransportSerializer> m_serializer;
+    std::unique_ptr<const TransportSerializer> m_serializer;
 
     NetPermissionFlags m_permissionFlags{NetPermissionFlags::None};