diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ae9ae09..5831e7a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,13 +1,11 @@
 IF (WIN32)
   ADD_DEFINITIONS (-D_CRT_SECURE_NO_WARNINGS)
 ELSE (WIN32)
-  SET (CMAKE_CXX_FLAGS "-Wall -fno-strict-aliasing")
+  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -fno-strict-aliasing")
 
   OPTION (APVLV_ENABLE_DEBUG "If build binary with debug infomations." OFF)
   IF (APVLV_ENABLE_DEBUG)
-    SET (CMAKE_CXX_FLAGS "-D_DEBUG -g ${CMAKE_CXX_FLAGS}")
-  ELSE (APVLV_ENABLE_DEBUG)
-    SET (CMAKE_CXX_FLAGS "-O2 ${CMAKE_CXX_FLAGS}")
+    SET (CMAKE_CXX_FLAGS "-D_DEBUG ${CMAKE_CXX_FLAGS}")
   ENDIF (APVLV_ENABLE_DEBUG)
 ENDIF (WIN32)