diff --git a/src/client/server/mod.rs b/src/client/server/mod.rs
index 7753185..96b2e5d 100644
--- a/src/client/server/mod.rs
+++ b/src/client/server/mod.rs
@@ -10,7 +10,7 @@ use std::thread::{spawn, sleep};
 use std::time::Duration as StdDuration;
 use client::conn::{Connection, NetConnection};
 use client::data::{Command, Config, Message, Response, User};
-use client::data::Command::{JOIN, NICK, NICKSERV, PART, PING, PRIVMSG, MODE};
+use client::data::Command::{JOIN, NICK, NICKSERV, PART, PING, PONG, PRIVMSG, MODE};
 use client::server::utils::ServerExt;
 use time::{Duration, Timespec, Tm, now};
 
@@ -57,6 +57,8 @@ struct ServerState {
     last_action_time: Mutex<Tm>,
     /// A thread-safe store for the last ping data.
     last_ping_data: Mutex<Option<Timespec>>,
+    /// A thread-safe check of pong reply.
+    waiting_pong_reply: Mutex<bool>,
 }
 
 impl ServerState {
@@ -69,10 +71,15 @@ impl ServerState {
             reconnect_count: Mutex::new(0),
             last_action_time: Mutex::new(now()),
             last_ping_data: Mutex::new(None),
+            waiting_pong_reply: Mutex::new(false),
         }
     }
 
     fn reconnect(&self) -> Result<()> {
+        let mut ping_data = self.last_ping_data.lock().unwrap();
+        *ping_data = None;
+        let mut waiting_pong_reply = self.waiting_pong_reply.lock().unwrap();
+        *waiting_pong_reply = false;
         self.conn.reconnect()
     }
 
@@ -86,19 +93,36 @@ impl ServerState {
         (now() - *time) > Duration::seconds(self.config.ping_time() as i64)
     }
 
+    fn last_action_time(&self) -> Tm {
+        *self.last_action_time.lock().unwrap()
+    }
+
     fn update_ping_data(&self, data: Timespec) {
         let mut ping_data = self.last_ping_data.lock().unwrap();
         *ping_data = Some(data);
-    }
-
-    fn ping_timeout_duration(&self) -> Duration {
-        Duration::seconds(self.config.ping_timeout() as i64)
+        let mut waiting_pong_reply = self.waiting_pong_reply.lock().unwrap();
+        *waiting_pong_reply = true;
     }
 
     fn last_ping_data(&self) -> Option<Timespec> {
         *self.last_ping_data.lock().unwrap()
     }
 
+    fn waiting_pong_reply(&self) -> bool {
+        *self.waiting_pong_reply.lock().unwrap()
+    }
+
+    fn check_pong(&self, data: &str) {
+        if let Some(ref time) = self.last_ping_data() {
+            let fmt = format!("{}", time.sec);
+            if fmt == data {
+                // found matching pong reply
+                let mut waiting_reply = self.waiting_pong_reply.lock().unwrap();
+                *waiting_reply = false;
+            }
+        }
+    }
+
     fn send_impl(&self, msg: Message) {
         while let Err(_) = self.write(msg.clone()) {
             let _ = self.reconnect().and_then(|_| self.identify());
@@ -202,30 +226,55 @@ impl IrcServer {
     where C: Connection + Send + Sync + 'static {
         let state = Arc::new(ServerState::new(conn, config));
         let ping_time = (state.config.ping_time() as i64) * 1000;
+        let ping_timeout = (state.config.ping_timeout() as i64) * 1000;
         let weak = Arc::downgrade(&state);
 
         spawn(move || while let Some(strong) = weak.upgrade() {
-            let sleep_dur = if let Some(time) = strong.last_ping_data() {
-                if now().to_timespec() - time > strong.ping_timeout_duration() {
+            let ping_idle_timespec = {
+                let last_action = strong.last_action_time().to_timespec();
+                if let Some(last_ping) = strong.last_ping_data() {
+                    if last_action < last_ping {
+                        last_ping
+                    } else {
+                        last_action
+                    }
+                } else {
+                    last_action
+                }
+            };
+            let now_timespec = now().to_timespec();
+            let sleep_dur_ping_time = ping_time - (now_timespec - ping_idle_timespec).num_milliseconds();
+            let sleep_dur_ping_timeout = if let Some(time) = strong.last_ping_data() {
+                ping_timeout - (now_timespec - time).num_milliseconds()
+            } else {
+                ping_timeout
+            };
+
+            if strong.waiting_pong_reply() && sleep_dur_ping_timeout < sleep_dur_ping_time {
+                // timeout check is earlier
+                let sleep_dur = sleep_dur_ping_timeout;
+                if sleep_dur > 0 {
+                    sleep(StdDuration::from_millis(sleep_dur as u64))
+                }
+                if strong.waiting_pong_reply() {
                     let _ = strong.reconnect();
                     while let Err(_) = strong.identify() {
                         let _ = strong.reconnect();
                     }
                 }
-                ping_time - (now().to_timespec() - time).num_milliseconds()
             } else {
-                ping_time
-            };
-
-            if sleep_dur > 0 {
-                sleep(StdDuration::from_millis(sleep_dur as u64))
-            }
-            if strong.should_ping() {
-                let data = now().to_timespec();
-                strong.update_ping_data(data);
-                let fmt = format!("{}", data.sec);
-                while let Err(_) = strong.write(PING(fmt.clone(), None)) {
-                    let _ = strong.reconnect();
+                let sleep_dur = sleep_dur_ping_time;
+                if sleep_dur > 0 {
+                    sleep(StdDuration::from_millis(sleep_dur as u64))
+                }
+                let now_timespec = now().to_timespec();
+                if strong.should_ping() {
+                    let data = now_timespec;
+                    strong.update_ping_data(data);
+                    let fmt = format!("{}", data.sec);
+                    while let Err(_) = strong.write(PING(fmt.clone(), None)) {
+                        let _ = strong.reconnect();
+                    }
                 }
             }
         });
@@ -269,6 +318,8 @@ impl IrcServer {
     fn handle_message(&self, msg: &Message) -> Result<()> {
         match msg.command {
             PING(ref data, _) => try!(self.send_pong(&data)),
+            PONG(_, Some(ref pingdata)) => self.state.check_pong(&pingdata),
+            PONG(ref pingdata, None) => self.state.check_pong(&pingdata),
             JOIN(ref chan, _, _) => self.handle_join(msg.source_nickname().unwrap_or(""), chan),
             PART(ref chan, _) => self.handle_part(msg.source_nickname().unwrap_or(""), chan),
             MODE(ref chan, ref mode, Some(ref user)) => self.handle_mode(chan, mode, user),