diff --git a/build/CMakeLists.txt b/build/CMakeLists.txt
index 168d1ab2..c01e0ba2 100644
--- a/build/CMakeLists.txt
+++ b/build/CMakeLists.txt
@@ -174,13 +174,13 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
   set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pipe")
   if (WITH_HARDENING)
     add_definitions( "-D_FORTIFY_SOURCE=2" )
-    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wformat -Wformat-security -Werror=format-security -Wno-unused-parameter" )
+    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wformat -Wformat-security -Werror=format-security" )
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fstack-protector --param ssp-buffer-size=4" )
   endif ()
 elseif (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
   # more tweaks
   if (NOT (MSVC OR MSYS OR APPLE))
-    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unused-parameter -stdlib=libstdc++" )
+    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unused-const-variable -Wno-overloaded-virtual -Wno-c99-extensions -stdlib=libstdc++" )
   endif()
 endif ()