--- a/mfbt/Attributes.h
+++ b/mfbt/Attributes.h
@@ -58,22 +58,24 @@
    /*
     * Per Clang documentation, "Note that marketing version numbers should not
     * be used to check for language features, as different vendors use different
     * numbering schemes. Instead, use the feature checking macros."
     */
 #  ifndef __has_extension
 #    define __has_extension __has_feature /* compatibility, for older versions of clang */
 #  endif
-#  if __has_extension(cxx_deleted_functions)
-#    define MOZ_HAVE_CXX11_DELETE
-#  endif
-#  if __has_extension(cxx_override_control)
-#    define MOZ_HAVE_CXX11_OVERRIDE
-#    define MOZ_HAVE_CXX11_FINAL         final
+#  if __cplusplus >= 201103L
+#    if __has_extension(cxx_deleted_functions)
+#      define MOZ_HAVE_CXX11_DELETE
+#    endif
+#    if __has_extension(cxx_override_control)
+#      define MOZ_HAVE_CXX11_OVERRIDE
+#      define MOZ_HAVE_CXX11_FINAL         final
+#    endif
 #  endif
 #  if __has_extension(cxx_strong_enums)
 #    define MOZ_HAVE_CXX11_ENUM_TYPE
 #    define MOZ_HAVE_CXX11_STRONG_ENUMS
 #  endif
 #  if __has_attribute(noinline)
 #    define MOZ_HAVE_NEVER_INLINE        __attribute__((noinline))
 #  endif