diff --git a/panda/src/pstatclient/pStatClientControlMessage.cxx b/panda/src/pstatclient/pStatClientControlMessage.cxx
index e7fd765547..5cbac136e4 100644
--- a/panda/src/pstatclient/pStatClientControlMessage.cxx
+++ b/panda/src/pstatclient/pStatClientControlMessage.cxx
@@ -39,6 +39,7 @@ encode(Datagram &datagram) const {
     datagram.add_string(_client_progname);
     datagram.add_uint16(_major_version);
     datagram.add_uint16(_minor_version);
+    datagram.add_uint32(_client_pid);
     break;
 
   case T_define_collectors:
@@ -86,6 +87,11 @@ decode(const Datagram &datagram, PStatClientVersion *version) {
       _major_version = source.get_uint16();
       _minor_version = source.get_uint16();
     }
+    if (source.get_remaining_size() >= 4) {
+      _client_pid = source.get_uint32();
+    } else {
+      _client_pid = -1;
+    }
     break;
 
   case T_define_collectors:
diff --git a/panda/src/pstatclient/pStatClientControlMessage.h b/panda/src/pstatclient/pStatClientControlMessage.h
index 97e7dede98..32a9f65f70 100644
--- a/panda/src/pstatclient/pStatClientControlMessage.h
+++ b/panda/src/pstatclient/pStatClientControlMessage.h
@@ -47,6 +47,7 @@ public:
   // Used for T_hello
   std::string _client_hostname;
   std::string _client_progname;
+  int _client_pid;
   int _major_version;
   int _minor_version;
 
diff --git a/panda/src/pstatclient/pStatClientImpl.cxx b/panda/src/pstatclient/pStatClientImpl.cxx
index f25b863b97..dcf0cdfef2 100644
--- a/panda/src/pstatclient/pStatClientImpl.cxx
+++ b/panda/src/pstatclient/pStatClientImpl.cxx
@@ -396,6 +396,11 @@ send_hello() {
   message._type = PStatClientControlMessage::T_hello;
   message._client_hostname = get_hostname();
   message._client_progname = _client_name;
+#ifdef _WIN32
+  message._client_pid = GetCurrentProcessId();
+#else
+  message._client_pid = getpid();
+#endif
   message._major_version = get_current_pstat_major_version();
   message._minor_version = get_current_pstat_minor_version();
 
diff --git a/pandatool/src/pstatserver/pStatMonitor.I b/pandatool/src/pstatserver/pStatMonitor.I
index 761b7b9a79..ac9f2e46f9 100644
--- a/pandatool/src/pstatserver/pStatMonitor.I
+++ b/pandatool/src/pstatserver/pStatMonitor.I
@@ -69,3 +69,11 @@ INLINE std::string PStatMonitor::
 get_client_progname() const {
   return _client_progname;
 }
+
+/**
+ * Returns the process id of the client, or -1 if it is not known.
+ */
+INLINE int PStatMonitor::
+get_client_pid() const {
+  return _client_pid;
+}
diff --git a/pandatool/src/pstatserver/pStatMonitor.cxx b/pandatool/src/pstatserver/pStatMonitor.cxx
index 09e22b093a..20444352c1 100644
--- a/pandatool/src/pstatserver/pStatMonitor.cxx
+++ b/pandatool/src/pstatserver/pStatMonitor.cxx
@@ -38,10 +38,11 @@ PStatMonitor::
  * indicates the client's reported hostname and program name.
  */
 void PStatMonitor::
-hello_from(const string &hostname, const string &progname) {
+hello_from(const string &hostname, const string &progname, int pid) {
   _client_known = true;
   _client_hostname = hostname;
   _client_progname = progname;
+  _client_pid = pid;
   got_hello();
 }
 
@@ -52,12 +53,13 @@ hello_from(const string &hostname, const string &progname) {
  * effect.
  */
 void PStatMonitor::
-bad_version(const string &hostname, const string &progname,
+bad_version(const string &hostname, const string &progname, int pid,
             int client_major, int client_minor,
             int server_major, int server_minor) {
   _client_known = true;
   _client_hostname = hostname;
   _client_progname = progname;
+  _client_pid = 0;
   got_bad_version(client_major, client_minor,
                   server_major, server_minor);
 }
diff --git a/pandatool/src/pstatserver/pStatMonitor.h b/pandatool/src/pstatserver/pStatMonitor.h
index f7e92073c4..8c1259c9f0 100644
--- a/pandatool/src/pstatserver/pStatMonitor.h
+++ b/pandatool/src/pstatserver/pStatMonitor.h
@@ -43,8 +43,10 @@ public:
   PStatMonitor(PStatServer *server);
   virtual ~PStatMonitor();
 
-  void hello_from(const std::string &hostname, const std::string &progname);
+  void hello_from(const std::string &hostname, const std::string &progname,
+                  int pid);
   void bad_version(const std::string &hostname, const std::string &progname,
+                   int pid,
                    int client_major, int client_minor,
                    int server_major, int server_minor);
   void set_client_data(PStatClientData *client_data);
@@ -63,6 +65,7 @@ public:
   INLINE bool is_client_known() const;
   INLINE std::string get_client_hostname() const;
   INLINE std::string get_client_progname() const;
+  INLINE int get_client_pid() const;
 
   PStatView &get_view(int thread_index);
   PStatView &get_level_view(int collector_index, int thread_index);
@@ -98,6 +101,7 @@ private:
   bool _client_known;
   std::string _client_hostname;
   std::string _client_progname;
+  int _client_pid;
 
   typedef pmap<int, PStatView> Views;
   Views _views;
diff --git a/pandatool/src/pstatserver/pStatReader.cxx b/pandatool/src/pstatserver/pStatReader.cxx
index 02b01f26a2..a2a1b4b7c9 100644
--- a/pandatool/src/pstatserver/pStatReader.cxx
+++ b/pandatool/src/pstatserver/pStatReader.cxx
@@ -195,11 +195,13 @@ handle_client_control_message(const PStatClientControlMessage &message) {
           (message._major_version == server_major_version &&
            message._minor_version > server_minor_version)) {
         _monitor->bad_version(message._client_hostname, message._client_progname,
+                              message._client_pid,
                               message._major_version, message._minor_version,
                               server_major_version, server_minor_version);
         _monitor->close();
       } else {
-        _monitor->hello_from(message._client_hostname, message._client_progname);
+        _monitor->hello_from(message._client_hostname, message._client_progname,
+                             message._client_pid);
       }
     }
     break;