diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29bdb68ea..d97e9549d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -573,13 +573,13 @@ if (CMAKE_COMPILER_IS_GNUCC)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wstrict-prototypes -Wmissing-prototypes")
   message(STATUS "Running with CMAKE_C_FLAGS ${CMAKE_C_FLAGS}")
   message(STATUS "Original CMAKE_C_FLAGS_DEBUG ${CMAKE_C_FLAGS_DEBUG}")
-  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS} -O -g ")
+  set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS} -g ")
   message(STATUS "Runing with CMAKE_C_FLAGS_DEBUG ${CMAKE_C_FLAGS_DEBUG}")
   message(STATUS "Original CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}")
-  set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS} -O3 -fomit-frame-pointer")
+  set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS} -O3 -fomit-frame-pointer -fstrict-aliasing -freorder-blocks -fsched-interblock")
   message(STATUS "Running with CMAKE_C_FLAGS_RELEASE ${CMAKE_C_FLAGS_RELEASE}")
 endif()
-add_definitions(-O -fstrict-aliasing -freorder-blocks -fsched-interblock -Wall)    
+add_definitions( -Wall)    
 add_definitions(-D_YAP_NOT_INSTALLED_=1 -DHAVE_CONFIG_H  -DLOW_LEVEL_TRACER=1 -DDEBUG=1)
 add_definitions(-DTHREADEAD_CODE=1)            
 add_definitions(-D_GNU_SOURCE=1 -D_XOPEN_SOURCE=700)