diff --git a/tdutils/td/utils/JsonBuilder.cpp b/tdutils/td/utils/JsonBuilder.cpp
index 26a918fa..da11b969 100644
--- a/tdutils/td/utils/JsonBuilder.cpp
+++ b/tdutils/td/utils/JsonBuilder.cpp
@@ -576,7 +576,7 @@ Slice JsonValue::get_type_name(Type type) {
   }
 }
 
-bool has_json_object_field(JsonObject &object, Slice name) {
+bool has_json_object_field(const JsonObject &object, Slice name) {
   for (auto &field_value : object) {
     if (field_value.first == name) {
       return true;
diff --git a/tdutils/td/utils/JsonBuilder.h b/tdutils/td/utils/JsonBuilder.h
index 4ae07239..35fff16c 100644
--- a/tdutils/td/utils/JsonBuilder.h
+++ b/tdutils/td/utils/JsonBuilder.h
@@ -816,7 +816,7 @@ auto json_array(const A &a, F &&f) {
   });
 }
 
-bool has_json_object_field(JsonObject &object, Slice name);
+bool has_json_object_field(const JsonObject &object, Slice name);
 
 Result<JsonValue> get_json_object_field(JsonObject &object, Slice name, JsonValue::Type type,
                                         bool is_optional = true) TD_WARN_UNUSED_RESULT;