diff --git a/td/telegram/files/FileId.h b/td/telegram/files/FileId.h
index c5b3337b..18175c61 100644
--- a/td/telegram/files/FileId.h
+++ b/td/telegram/files/FileId.h
@@ -40,8 +40,8 @@ class FileId {
     return id;
   }
 
-  int32 get() {
-    time_ = std::time(nullptr);
+  int32 get() const {
+    const_cast<FileId*>(this)->time_ = std::time(nullptr);
     return id;
   }