diff --git a/td/mtproto/SessionConnection.cpp b/td/mtproto/SessionConnection.cpp
index 96284fbfe..f6605215a 100644
--- a/td/mtproto/SessionConnection.cpp
+++ b/td/mtproto/SessionConnection.cpp
@@ -800,8 +800,8 @@ void SessionConnection::flush_packet() {
   if (mode_ == Mode::HttpLongPoll) {
     max_delay = HTTP_MAX_DELAY;
     max_after = HTTP_MAX_AFTER;
-    max_wait = min(http_max_wait(),
-                   static_cast<int>(1000 * max(0.1, ping_disconnect_delay() + last_pong_at_ - Time::now_cached() - 1)));
+    auto time_to_disconnect = ping_disconnect_delay() + last_pong_at_ - Time::now_cached();
+    max_wait = min(http_max_wait(), static_cast<int>(1000 * max(0.1, time_to_disconnect - rtt())));
   } else if (mode_ == Mode::Http) {
     max_delay = HTTP_MAX_DELAY;
     max_after = HTTP_MAX_AFTER;
diff --git a/td/mtproto/SessionConnection.h b/td/mtproto/SessionConnection.h
index 033732940..b4ec6a39c 100644
--- a/td/mtproto/SessionConnection.h
+++ b/td/mtproto/SessionConnection.h
@@ -125,7 +125,7 @@ class SessionConnection
   bool online_flag_ = false;
 
   int rtt() const {
-    return max(2, static_cast<int>(raw_connection_->rtt_ * 1.5));
+    return max(2, static_cast<int>(raw_connection_->rtt_ * 1.5 + 1));
   }
 
   int32 ping_disconnect_delay() const {