diff --git a/td/telegram/Location.cpp b/td/telegram/Location.cpp
index e4c09bcf7..931eac788 100644
--- a/td/telegram/Location.cpp
+++ b/td/telegram/Location.cpp
@@ -151,6 +151,10 @@ Location &Venue::location() {
   return location_;
 }
 
+const Location &Venue::location() const {
+  return location_;
+}
+
 tl_object_ptr<td_api::venue> Venue::get_venue_object() const {
   return make_tl_object<td_api::venue>(location_.get_location_object(), title_, address_, provider_, id_, type_);
 }
diff --git a/td/telegram/Location.h b/td/telegram/Location.h
index 771ccd7de..9d7ecbec1 100644
--- a/td/telegram/Location.h
+++ b/td/telegram/Location.h
@@ -27,7 +27,7 @@ class Location {
   bool is_empty_ = true;
   double latitude_ = 0.0;
   double longitude_ = 0.0;
-  int64 access_hash_ = 0;
+  mutable int64 access_hash_ = 0;
 
   friend bool operator==(const Location &lhs, const Location &rhs);
   friend bool operator!=(const Location &lhs, const Location &rhs);
@@ -69,7 +69,7 @@ class Location {
     return access_hash_;
   }
 
-  void set_access_hash(int64 access_hash) {
+  void set_access_hash(int64 access_hash) const {
     access_hash_ = access_hash;
   }
 
@@ -139,6 +139,8 @@ class Venue {
 
   Location &location();
 
+  const Location &location() const;
+
   tl_object_ptr<td_api::venue> get_venue_object() const;
 
   tl_object_ptr<telegram_api::inputMediaVenue> get_input_media_venue() const;
diff --git a/td/telegram/MessageContent.cpp b/td/telegram/MessageContent.cpp
index 3e3c20600..23c0aa44f 100644
--- a/td/telegram/MessageContent.cpp
+++ b/td/telegram/MessageContent.cpp
@@ -2679,7 +2679,7 @@ void set_message_content_web_page_id(MessageContent *content, WebPageId web_page
   static_cast<MessageText *>(content)->web_page_id = web_page_id;
 }
 
-static void merge_location_access_hash(Location &first, Location &second) {
+static void merge_location_access_hash(const Location &first, const Location &second) {
   if (second.get_access_hash() != 0) {
     first.set_access_hash(second.get_access_hash());
   } else {
@@ -2709,7 +2709,7 @@ static bool need_message_text_changed_warning(const MessageText *old_content, co
   return true;
 }
 
-void merge_message_contents(Td *td, MessageContent *old_content, MessageContent *new_content,
+void merge_message_contents(Td *td, const MessageContent *old_content, MessageContent *new_content,
                             bool need_message_changed_warning, DialogId dialog_id, bool need_merge_files,
                             bool &is_content_changed, bool &need_update) {
   MessageContentType content_type = new_content->get_type();
@@ -2812,8 +2812,8 @@ void merge_message_contents(Td *td, MessageContent *old_content, MessageContent
       break;
     }
     case MessageContentType::LiveLocation: {
-      auto old_ = static_cast<MessageLiveLocation *>(old_content);
-      auto new_ = static_cast<MessageLiveLocation *>(new_content);
+      auto old_ = static_cast<const MessageLiveLocation *>(old_content);
+      auto new_ = static_cast<const MessageLiveLocation *>(new_content);
       if (old_->location != new_->location) {
         need_update = true;
       }
@@ -2827,8 +2827,8 @@ void merge_message_contents(Td *td, MessageContent *old_content, MessageContent
       break;
     }
     case MessageContentType::Location: {
-      auto old_ = static_cast<MessageLocation *>(old_content);
-      auto new_ = static_cast<MessageLocation *>(new_content);
+      auto old_ = static_cast<const MessageLocation *>(old_content);
+      auto new_ = static_cast<const MessageLocation *>(new_content);
       if (old_->location != new_->location) {
         need_update = true;
       }
@@ -2903,8 +2903,8 @@ void merge_message_contents(Td *td, MessageContent *old_content, MessageContent
       break;
     }
     case MessageContentType::Venue: {
-      auto old_ = static_cast<MessageVenue *>(old_content);
-      auto new_ = static_cast<MessageVenue *>(new_content);
+      auto old_ = static_cast<const MessageVenue *>(old_content);
+      auto new_ = static_cast<const MessageVenue *>(new_content);
       if (old_->venue != new_->venue) {
         need_update = true;
       }
diff --git a/td/telegram/MessageContent.h b/td/telegram/MessageContent.h
index 06bf06df3..931ba82c2 100644
--- a/td/telegram/MessageContent.h
+++ b/td/telegram/MessageContent.h
@@ -179,7 +179,7 @@ WebPageId get_message_content_web_page_id(const MessageContent *content);
 
 void set_message_content_web_page_id(MessageContent *content, WebPageId web_page_id);
 
-void merge_message_contents(Td *td, MessageContent *old_content, MessageContent *new_content,
+void merge_message_contents(Td *td, const MessageContent *old_content, MessageContent *new_content,
                             bool need_message_changed_warning, DialogId dialog_id, bool need_merge_files,
                             bool &is_content_changed, bool &need_update);