diff --git a/tddb/td/db/TQueue.cpp b/tddb/td/db/TQueue.cpp
index a126c7bd7..acc0ff721 100644
--- a/tddb/td/db/TQueue.cpp
+++ b/tddb/td/db/TQueue.cpp
@@ -186,11 +186,7 @@ class TQueueImpl : public TQueue {
     if (it == queues_.end()) {
       return EventId();
     }
-    auto &q = it->second;
-    if (q.events.empty()) {
-      return q.tail_id;
-    }
-    return q.events.begin()->first;
+    return get_queue_head(it->second);
   }
 
   EventId get_tail(QueueId queue_id) const override {
@@ -227,7 +223,7 @@ class TQueueImpl : public TQueue {
     if (from_id.value() > q.tail_id.value() + 10) {
       return Status::Error("Specified from_id is in the future");
     }
-    if (from_id.value() < q.tail_id.value() - static_cast<int32>(MAX_QUEUE_EVENTS) * 2) {
+    if (from_id.value() < get_queue_head(q).value() - MAX_QUEUE_EVENTS) {
       return Status::Error("Specified from_id is in the past");
     }
 
@@ -267,7 +263,7 @@ class TQueueImpl : public TQueue {
     return deleted_events;
   }
 
-  size_t get_size(QueueId queue_id) override {
+  size_t get_size(QueueId queue_id) const override {
     auto it = queues_.find(queue_id);
     if (it == queues_.end()) {
       return 0;
@@ -294,7 +290,14 @@ class TQueueImpl : public TQueue {
   std::set<std::pair<int32, QueueId>> queue_gc_at_;
   unique_ptr<StorageCallback> callback_;
 
-  static size_t get_size(Queue &q) {
+  static EventId get_queue_head(const Queue &q) {
+    if (q.events.empty()) {
+      return q.tail_id;
+    }
+    return q.events.begin()->first;
+  }
+
+  static size_t get_size(const Queue &q) {
     if (q.events.empty()) {
       return 0;
     }
diff --git a/tddb/td/db/TQueue.h b/tddb/td/db/TQueue.h
index 14b46b0ef..58efc283a 100644
--- a/tddb/td/db/TQueue.h
+++ b/tddb/td/db/TQueue.h
@@ -111,7 +111,7 @@ class TQueue {
   virtual Result<size_t> get(QueueId queue_id, EventId from_id, bool forget_previous, int32 unix_time_now,
                              MutableSpan<Event> &result_events) = 0;
 
-  virtual size_t get_size(QueueId queue_id) = 0;
+  virtual size_t get_size(QueueId queue_id) const = 0;
 
   virtual int64 run_gc(int32 unix_time_now) = 0;
   virtual void close(Promise<> promise) = 0;