diff --git a/CMake/CTestCustom.cmake.in b/CMake/CTestCustom.cmake.in
index 81a8fb0aab89d12bab318bb86f2c4607b264e111..ca3fc4ba0de0f99c8a8f946b9eba3c9709d877ac 100644
--- a/CMake/CTestCustom.cmake.in
+++ b/CMake/CTestCustom.cmake.in
@@ -53,4 +53,5 @@ SET(CTEST_CUSTOM_WARNING_EXCEPTION
   "Fl_Image.H:.*warning:.*dereferencing type-punned pointer will break strict-aliasing rules.*"
   "warning -.: directory name .* does not exist"
   "ld.*warning.*duplicate dylib.*"
+  "pyconfig.h:.*warning:.*_XOPEN_SOURCE.*redefined"
   )