diff --git a/Libraries/LibAudio/AClientConnection.cpp b/Libraries/LibAudio/AClientConnection.cpp
index c8ec8758a9a..b0283680e70 100644
--- a/Libraries/LibAudio/AClientConnection.cpp
+++ b/Libraries/LibAudio/AClientConnection.cpp
@@ -9,8 +9,7 @@ AClientConnection::AClientConnection()
 
 void AClientConnection::handshake()
 {
-    auto response = send_sync<AudioServer::Greet>(getpid());
-    set_server_pid(response->server_pid());
+    auto response = send_sync<AudioServer::Greet>();
     set_my_client_id(response->client_id());
 }
 
diff --git a/Libraries/LibGUI/GWindowServerConnection.cpp b/Libraries/LibGUI/GWindowServerConnection.cpp
index fd4d533c869..b04ed1c7d0d 100644
--- a/Libraries/LibGUI/GWindowServerConnection.cpp
+++ b/Libraries/LibGUI/GWindowServerConnection.cpp
@@ -20,8 +20,7 @@ GWindowServerConnection& GWindowServerConnection::the()
 
 void GWindowServerConnection::handshake()
 {
-    auto response = send_sync<WindowServer::Greet>(getpid());
-    set_server_pid(response->server_pid());
+    auto response = send_sync<WindowServer::Greet>();
     set_my_client_id(response->client_id());
     GDesktop::the().did_receive_screen_rect({}, response->screen_rect());
 }
diff --git a/Libraries/LibIPC/IClientConnection.h b/Libraries/LibIPC/IClientConnection.h
index 7e816b5dcdb..418365c23c6 100644
--- a/Libraries/LibIPC/IClientConnection.h
+++ b/Libraries/LibIPC/IClientConnection.h
@@ -55,6 +55,13 @@ public:
         , m_socket(socket)
         , m_client_id(client_id)
     {
+        ASSERT(socket.is_connected());
+        ucred creds;
+        socklen_t creds_size = sizeof(creds);
+        if (getsockopt(m_socket->fd(), SOL_SOCKET, SO_PEERCRED, &creds, &creds_size) < 0) {
+            ASSERT_NOT_REACHED();
+        }
+        m_client_pid = creds.pid;
         add_child(socket);
         m_socket->on_ready_to_read = [this] { drain_messages_from_client(); };
     }
@@ -142,7 +149,6 @@ public:
 
     int client_id() const { return m_client_id; }
     pid_t client_pid() const { return m_client_pid; }
-    void set_client_pid(pid_t pid) { m_client_pid = pid; }
 
     virtual void die() = 0;
 
diff --git a/Libraries/LibIPC/IServerConnection.h b/Libraries/LibIPC/IServerConnection.h
index 70133ee9e98..60f61459140 100644
--- a/Libraries/LibIPC/IServerConnection.h
+++ b/Libraries/LibIPC/IServerConnection.h
@@ -39,12 +39,19 @@ public:
             usleep(10000);
             --retries;
         }
+
+        ucred creds;
+        socklen_t creds_size = sizeof(creds);
+        if (getsockopt(m_connection->fd(), SOL_SOCKET, SO_PEERCRED, &creds, &creds_size) < 0) {
+            ASSERT_NOT_REACHED();
+        }
+        m_server_pid = creds.pid;
+
         ASSERT(m_connection->is_connected());
     }
 
     virtual void handshake() = 0;
 
-    void set_server_pid(pid_t pid) { m_server_pid = pid; }
     pid_t server_pid() const { return m_server_pid; }
     void set_my_client_id(int id) { m_my_client_id = id; }
     int my_client_id() const { return m_my_client_id; }
diff --git a/Libraries/LibProtocol/Client.cpp b/Libraries/LibProtocol/Client.cpp
index dd7b1de771b..9ec7928c032 100644
--- a/Libraries/LibProtocol/Client.cpp
+++ b/Libraries/LibProtocol/Client.cpp
@@ -12,8 +12,7 @@ Client::Client()
 
 void Client::handshake()
 {
-    auto response = send_sync<ProtocolServer::Greet>(getpid());
-    set_server_pid(response->server_pid());
+    auto response = send_sync<ProtocolServer::Greet>();
     set_my_client_id(response->client_id());
 }
 
diff --git a/Servers/AudioServer/ASClientConnection.cpp b/Servers/AudioServer/ASClientConnection.cpp
index 5dd25f94fa8..caf64d64792 100644
--- a/Servers/AudioServer/ASClientConnection.cpp
+++ b/Servers/AudioServer/ASClientConnection.cpp
@@ -48,10 +48,9 @@ void ASClientConnection::did_change_muted_state(Badge<ASMixer>, bool muted)
     post_message(AudioClient::MutedStateChanged(muted));
 }
 
-OwnPtr<AudioServer::GreetResponse> ASClientConnection::handle(const AudioServer::Greet& message)
+OwnPtr<AudioServer::GreetResponse> ASClientConnection::handle(const AudioServer::Greet&)
 {
-    set_client_pid(message.client_pid());
-    return make<AudioServer::GreetResponse>(getpid(), client_id());
+    return make<AudioServer::GreetResponse>(client_id());
 }
 
 OwnPtr<AudioServer::GetMainMixVolumeResponse> ASClientConnection::handle(const AudioServer::GetMainMixVolume&)
diff --git a/Servers/AudioServer/AudioServer.ipc b/Servers/AudioServer/AudioServer.ipc
index b48cbc6c06b..b48dcd7e464 100644
--- a/Servers/AudioServer/AudioServer.ipc
+++ b/Servers/AudioServer/AudioServer.ipc
@@ -1,7 +1,7 @@
 endpoint AudioServer = 85
 {
     // Basic protocol
-    Greet(i32 client_pid) => (i32 server_pid, i32 client_id)
+    Greet() => (i32 client_id)
 
     // Mixer functions
     SetMuted(bool muted) => ()
diff --git a/Servers/ProtocolServer/PSClientConnection.cpp b/Servers/ProtocolServer/PSClientConnection.cpp
index fe7658720fd..6fcea878a5a 100644
--- a/Servers/ProtocolServer/PSClientConnection.cpp
+++ b/Servers/ProtocolServer/PSClientConnection.cpp
@@ -65,10 +65,9 @@ void PSClientConnection::did_progress_download(Badge<Download>, Download& downlo
     post_message(ProtocolClient::DownloadProgress(download.id(), download.total_size(), download.downloaded_size()));
 }
 
-OwnPtr<ProtocolServer::GreetResponse> PSClientConnection::handle(const ProtocolServer::Greet& message)
+OwnPtr<ProtocolServer::GreetResponse> PSClientConnection::handle(const ProtocolServer::Greet&)
 {
-    set_client_pid(message.client_pid());
-    return make<ProtocolServer::GreetResponse>(getpid(), client_id());
+    return make<ProtocolServer::GreetResponse>(client_id());
 }
 
 OwnPtr<ProtocolServer::DisownSharedBufferResponse> PSClientConnection::handle(const ProtocolServer::DisownSharedBuffer& message)
diff --git a/Servers/ProtocolServer/ProtocolServer.ipc b/Servers/ProtocolServer/ProtocolServer.ipc
index 6ed9eba6232..698273c3aab 100644
--- a/Servers/ProtocolServer/ProtocolServer.ipc
+++ b/Servers/ProtocolServer/ProtocolServer.ipc
@@ -1,7 +1,7 @@
 endpoint ProtocolServer = 9
 {
     // Basic protocol
-    Greet(i32 client_pid) => (i32 server_pid, i32 client_id)
+    Greet() => (i32 client_id)
 
     // FIXME: It would be nice if the kernel provided a way to avoid this
     DisownSharedBuffer(i32 shared_buffer_id) => ()
diff --git a/Servers/WindowServer/WSClientConnection.cpp b/Servers/WindowServer/WSClientConnection.cpp
index 0e233877069..74a59319158 100644
--- a/Servers/WindowServer/WSClientConnection.cpp
+++ b/Servers/WindowServer/WSClientConnection.cpp
@@ -598,10 +598,9 @@ void WSClientConnection::handle(const WindowServer::WM_SetWindowMinimized& messa
     window.set_minimized(message.minimized());
 }
 
-OwnPtr<WindowServer::GreetResponse> WSClientConnection::handle(const WindowServer::Greet& message)
+OwnPtr<WindowServer::GreetResponse> WSClientConnection::handle(const WindowServer::Greet&)
 {
-    set_client_pid(message.client_pid());
-    return make<WindowServer::GreetResponse>(getpid(), client_id(), WSScreen::the().rect());
+    return make<WindowServer::GreetResponse>(client_id(), WSScreen::the().rect());
 }
 
 bool WSClientConnection::is_showing_modal_window() const
diff --git a/Servers/WindowServer/WindowServer.ipc b/Servers/WindowServer/WindowServer.ipc
index 3f78821d377..61ab691b9e2 100644
--- a/Servers/WindowServer/WindowServer.ipc
+++ b/Servers/WindowServer/WindowServer.ipc
@@ -1,6 +1,6 @@
 endpoint WindowServer = 2
 {
-    Greet(i32 client_pid) => (i32 server_pid, i32 client_id, Rect screen_rect)
+    Greet() => (i32 client_id, Rect screen_rect)
 
     CreateMenubar() => (i32 menubar_id)
     DestroyMenubar(i32 menubar_id) => ()