diff --git a/Source/dvlnet/frame_queue.cpp b/Source/dvlnet/frame_queue.cpp
index dfe358415..80054b2e0 100644
--- a/Source/dvlnet/frame_queue.cpp
+++ b/Source/dvlnet/frame_queue.cpp
@@ -7,7 +7,7 @@
 namespace devilution {
 namespace net {
 
-framesize_t frame_queue::size()
+framesize_t frame_queue::size() const
 {
 	return current_size;
 }
diff --git a/Source/dvlnet/frame_queue.h b/Source/dvlnet/frame_queue.h
index 16ee8a41c..7c5c0cf19 100644
--- a/Source/dvlnet/frame_queue.h
+++ b/Source/dvlnet/frame_queue.h
@@ -29,7 +29,7 @@ private:
 	std::deque<buffer_t> buffer_deque;
 	framesize_t nextsize = 0;
 
-	framesize_t size();
+	framesize_t size() const;
 	buffer_t read(framesize_t s);
 
 public:
diff --git a/Source/dvlnet/packet.cpp b/Source/dvlnet/packet.cpp
index f460dfddc..483ac1447 100644
--- a/Source/dvlnet/packet.cpp
+++ b/Source/dvlnet/packet.cpp
@@ -78,14 +78,14 @@ packet_type packet::type()
 	return m_type;
 }
 
-plr_t packet::src()
+plr_t packet::src() const
 {
 	if (!have_decrypted)
 		ABORT();
 	return m_src;
 }
 
-plr_t packet::dest()
+plr_t packet::dest() const
 {
 	if (!have_decrypted)
 		ABORT();
diff --git a/Source/dvlnet/packet.h b/Source/dvlnet/packet.h
index ea6339591..5e27eeabc 100644
--- a/Source/dvlnet/packet.h
+++ b/Source/dvlnet/packet.h
@@ -91,8 +91,8 @@ public:
 	const buffer_t &data();
 
 	packet_type type();
-	plr_t src();
-	plr_t dest();
+	plr_t src() const;
+	plr_t dest() const;
 	const buffer_t &message();
 	turn_t turn();
 	cookie_t cookie();
diff --git a/Source/dvlnet/protocol_zt.cpp b/Source/dvlnet/protocol_zt.cpp
index 75f430bb3..665291938 100644
--- a/Source/dvlnet/protocol_zt.cpp
+++ b/Source/dvlnet/protocol_zt.cpp
@@ -92,7 +92,7 @@ bool protocol_zt::send(const endpoint &peer, const buffer_t &data)
 	return true;
 }
 
-bool protocol_zt::send_oob(const endpoint &peer, const buffer_t &data)
+bool protocol_zt::send_oob(const endpoint &peer, const buffer_t &data) const
 {
 	struct sockaddr_in6 in6 {
 	};
diff --git a/Source/dvlnet/protocol_zt.h b/Source/dvlnet/protocol_zt.h
index ab3d6f204..604b807fc 100644
--- a/Source/dvlnet/protocol_zt.h
+++ b/Source/dvlnet/protocol_zt.h
@@ -68,7 +68,7 @@ public:
 	~protocol_zt();
 	void disconnect(const endpoint &peer);
 	bool send(const endpoint &peer, const buffer_t &data);
-	bool send_oob(const endpoint &peer, const buffer_t &data);
+	bool send_oob(const endpoint &peer, const buffer_t &data) const;
 	bool send_oob_mc(const buffer_t &data);
 	bool recv(endpoint &peer, buffer_t &data);
 	bool get_disconnected(endpoint &peer);