diff --git a/Modules/Compiler/GNU-CXX-FeatureTests.cmake b/Modules/Compiler/GNU-CXX-FeatureTests.cmake
index 5fc3debb0..d18adaff0 100644
--- a/Modules/Compiler/GNU-CXX-FeatureTests.cmake
+++ b/Modules/Compiler/GNU-CXX-FeatureTests.cmake
@@ -6,6 +6,8 @@ set(_cmake_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 404")
 
 set(GNU50_CXX14 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 500 && __cplusplus >= 201402L")
 set(_cmake_feature_test_cxx_variable_templates "${GNU50_CXX14}")
+set(_cmake_feature_test_cxx_relaxed_constexpr "${GNU50_CXX14}")
+set(_cmake_feature_test_cxx_aggregate_default_initializers "${GNU50_CXX14}")
 
 # GNU 4.9 in c++14 mode sets __cplusplus to 201300L, so don't test for the
 # correct value of it below.