diff --git a/protocols/inspircd.py b/protocols/inspircd.py
index ba02acb..a2e6a19 100644
--- a/protocols/inspircd.py
+++ b/protocols/inspircd.py
@@ -308,14 +308,6 @@ class InspIRCdProtocol(TS6BaseProtocol):
                 self.call_hooks([self.sid, 'CHGNAME',
                                    {'target': target, 'newgecos': text}])
 
-    def ping(self, source=None, target=None):
-        """Sends a PING to a target server. Periodic PINGs are sent to our uplink
-        automatically by the Irc() internals; plugins shouldn't have to use this."""
-        source = source or self.sid
-        target = target or self.uplink
-        if not (target is None or source is None):
-            self._send_with_prefix(source, 'PING %s %s' % (source, target))
-
     def numeric(self, source, numeric, target, text):
         """Sends raw numerics from a server to a remote client."""
         # InspIRCd 2.0 syntax (undocumented):
diff --git a/protocols/ircs2s_common.py b/protocols/ircs2s_common.py
index 0bb8bd3..6667284 100644
--- a/protocols/ircs2s_common.py
+++ b/protocols/ircs2s_common.py
@@ -256,7 +256,7 @@ class IRCCommonProtocol(IRCNetwork):
             log.debug('(%s) handle_005: got umode callerid=%r', self.name, self.umodes['callerid'])
 
     def _send_with_prefix(self, source, msg, **kwargs):
-        """Sends a RFC 459-style raw command from the given sender."""
+        """Sends a RFC1459-style raw command from the given sender."""
         self.send(':%s %s' % (self._expandPUID(source), msg), **kwargs)
 
     def _expandPUID(self, uid):
@@ -358,6 +358,19 @@ class IRCS2SProtocol(IRCCommonProtocol):
         self._send_with_prefix(client, msg)
         self.handle_part(client, 'PART', [channel])
 
+    def ping(self, source=None, target=None):
+        """Sends a PING to a target server.
+
+        This is mostly used by PyLink internals to check whether the remote link is up."""
+        source = source or self.sid
+        if source is None:  # Source hasn't been initialized yet; ignore this command
+            return
+
+        if target is not None:
+            self._send_with_prefix(source, 'PING %s %s' % (source, target))
+        else:
+            self._send_with_prefix(source, 'PING %s' % source)
+
     def quit(self, numeric, reason):
         """Quits a PyLink client."""
         if self.is_internal_client(numeric):
diff --git a/protocols/ts6.py b/protocols/ts6.py
index 5a67e30..10943e0 100644
--- a/protocols/ts6.py
+++ b/protocols/ts6.py
@@ -242,17 +242,6 @@ class TS6Protocol(TS6BaseProtocol):
             raise NotImplementedError("Changing field %r of a client is "
                                       "unsupported by this protocol." % field)
 
-    def ping(self, source=None, target=None):
-        """Sends a PING to a target server. Periodic PINGs are sent to our uplink
-        automatically by the Irc() internals; plugins shouldn't have to use this."""
-        source = source or self.sid
-        if source is None:
-            return
-        if target is not None:
-            self._send_with_prefix(source, 'PING %s %s' % (source, target))
-        else:
-            self._send_with_prefix(source, 'PING %s' % source)
-
     ### Core / handlers
 
     def post_connect(self):