Index: libnm-qt/CMakeLists.txt
===================================================================
--- libnm-qt.orig/CMakeLists.txt	2014-03-03 10:42:12.604751333 +0100
+++ libnm-qt/CMakeLists.txt	2014-03-03 11:01:00.846811289 +0100
@@ -36,7 +36,7 @@
 include(CheckCXXCompilerFlag)
 check_cxx_compiler_flag("-Werror=return-type" HAVE_GCC_ERROR_RETURN_TYPE)
 if (HAVE_GCC_ERROR_RETURN_TYPE)
-    set(CMAKE_CXX_FLAGS "-Werror=return-type")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror=return-type")
 endif()
 
 include_directories(
