diff --git a/td/mtproto/SessionConnection.cpp b/td/mtproto/SessionConnection.cpp
index 2a53880dd..37d0a75b8 100644
--- a/td/mtproto/SessionConnection.cpp
+++ b/td/mtproto/SessionConnection.cpp
@@ -171,6 +171,10 @@ namespace mtproto {
  *
  */
 
+inline StringBuilder &operator<<(StringBuilder &string_builder, const SessionConnection::MsgInfo &info) {
+  return string_builder << "[msg_id:" << format::as_hex(info.message_id) << "][seq_no:" << info.seq_no << ']';
+}
+
 unique_ptr<RawConnection> SessionConnection::move_as_raw_connection() {
   was_moved_ = true;
   return std::move(raw_connection_);
diff --git a/td/mtproto/SessionConnection.h b/td/mtproto/SessionConnection.h
index b7881b574..1cea16d33 100644
--- a/td/mtproto/SessionConnection.h
+++ b/td/mtproto/SessionConnection.h
@@ -53,16 +53,6 @@ namespace mtproto {
 
 class AuthData;
 
-struct MsgInfo {
-  uint64 message_id;
-  int32 seq_no;
-  size_t size;
-};
-
-inline StringBuilder &operator<<(StringBuilder &string_builder, const MsgInfo &info) {
-  return string_builder << "[msg_id:" << format::as_hex(info.message_id) << "][seq_no:" << info.seq_no << ']';
-}
-
 class SessionConnection final
     : public Named
     , private RawConnection::Callback {
@@ -133,6 +123,14 @@ class SessionConnection final
   static constexpr double QUERY_DELAY = 0.001;          // 0.001s
   static constexpr double RESEND_ANSWER_DELAY = 0.001;  // 0.001s
 
+  struct MsgInfo {
+    uint64 message_id;
+    int32 seq_no;
+    size_t size;
+  };
+
+  friend StringBuilder &operator<<(StringBuilder &string_builder, const MsgInfo &info);
+
   bool online_flag_ = false;
   bool is_main_ = false;
   bool was_moved_ = false;