diff --git a/tdutils/td/utils/JsonBuilder.cpp b/tdutils/td/utils/JsonBuilder.cpp
index b4071ecdff05..a0aebb61c32c 100644
--- a/tdutils/td/utils/JsonBuilder.cpp
+++ b/tdutils/td/utils/JsonBuilder.cpp
@@ -542,6 +542,13 @@ Slice JsonValue::get_type_name(Type type) {
   }
 }
 
+JsonObject::JsonObject(vector<std::pair<Slice, JsonValue>> &&field_values) : field_values_(std::move(field_values)) {
+}
+
+size_t JsonObject::field_count() const {
+  return field_values_.size();
+}
+
 JsonValue JsonObject::extract_field(Slice name) {
   for (auto &field_value : field_values_) {
     if (field_value.first == name) {
diff --git a/tdutils/td/utils/JsonBuilder.h b/tdutils/td/utils/JsonBuilder.h
index 1b3e9ed7eb0d..3989cf76e7f6 100644
--- a/tdutils/td/utils/JsonBuilder.h
+++ b/tdutils/td/utils/JsonBuilder.h
@@ -464,8 +464,7 @@ class JsonObject {
 
   JsonObject() = default;
 
-  explicit JsonObject(vector<std::pair<Slice, JsonValue>> &&field_values) : field_values_(std::move(field_values)) {
-  }
+  explicit JsonObject(vector<std::pair<Slice, JsonValue>> &&field_values);
 
   JsonObject(const JsonObject &) = delete;
   JsonObject &operator=(const JsonObject &) = delete;
@@ -473,9 +472,7 @@ class JsonObject {
   JsonObject &operator=(JsonObject &&) = default;
   ~JsonObject() = default;
 
-  size_t field_count() const {
-    return field_values_.size();
-  }
+  size_t field_count() const;
 
   JsonValue extract_field(Slice name);