diff -ru widelands-build18-src.orig/CMakeLists.txt widelands-build18-src/CMakeLists.txt
--- widelands-build18-src.orig/CMakeLists.txt	2014-02-22 04:06:51.000000000 -0500
+++ widelands-build18-src/CMakeLists.txt	2016-03-23 23:04:50.536259815 -0400
@@ -271,7 +271,7 @@
   ENDIF (WLBUILD_COMPILERVERSION_REP STREQUAL "4.5.1" OR WLBUILD_COMPILERVERSION_REP STREQUAL "4.5.2")
 ENDIF (CMAKE_COMPILER_IS_GNUCXX)
 
-set (CMAKE_CXX_FLAGS_RELEASE "${WL_COMPILERFLAG_CXXSTD} ${WL_COMPILERFLAG_OPTIMIZATIONS} -DNDEBUG${WL_COMPILERFLAG_OLDSTYLECAST}${WL_COMPILERFLAG_GENERICWARNINGS}${WL_COMPILERFLAG_EXTRAWARNINGS}${WL_COMPILERFLAG_GCCWARNINGS}${WL_COMPILERFLAG_STRICT}" CACHE STRING "Set by widelands CMakeLists.txt" FORCE)
+set (CMAKE_CXX_FLAGS_RELEASE "${WL_COMPILERFLAG_CXXSTD} -DNDEBUG${WL_COMPILERFLAG_OLDSTYLECAST}${WL_COMPILERFLAG_GENERICWARNINGS}${WL_COMPILERFLAG_EXTRAWARNINGS}${WL_COMPILERFLAG_GCCWARNINGS}${WL_COMPILERFLAG_STRICT}" CACHE STRING "Set by widelands CMakeLists.txt" FORCE)
 
 #If building with MSVC, then check for 3rdparty libs
 if (DEFINED MSVC)