Index: CMakeLists.txt
===================================================================
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,6 @@ cmake_minimum_required(VERSION 3.5.1)
 project(CrossGuid)
 
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/cmake")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3")
 
 option(XG_TESTS "Build test runner" ON)
 
