diff --git a/include/struct_mapping/mapper.h b/include/struct_mapping/mapper.h
index f91ae5f..bf4cc4c 100644
--- a/include/struct_mapping/mapper.h
+++ b/include/struct_mapping/mapper.h
@@ -191,9 +191,8 @@ inline void map_struct_to_json(
 
  					json_data << "null";
 				}
-			}
-
-			first_element = false;
+				first_element = false;
+			}			
 		};
 
 	detail::IterateOver::set<bool> = [&] (const std::string& name, bool value)
@@ -508,4 +507,4 @@ inline void map_struct_to_json(
 	detail::Object<T>::iterate_over(source_struct, "");
 }
 
-} // struct_mapping
\ No newline at end of file
+} // struct_mapping