diff --git a/include/pqxx/internal/cxx-features.hxx b/include/pqxx/internal/cxx-features.hxx
deleted file mode 100644
index 2667baa55..000000000
--- a/include/pqxx/internal/cxx-features.hxx
+++ /dev/null
@@ -1,43 +0,0 @@
-/** C++ feature test macros.
- *
- * Flags defining available C++ features.  These will progressively replace
- * feature tests at the build stage.
- *
- * Why define these and not use the standard C++ macros directly?  To avoid
- * annoying warnings.  The standard macros rely on te fact that an undefined
- * macro, used as a boolean in a preprocessor conditional, evaluates as false.
- * This is pretty fundamental to how the standard feature test macros work:
- * you just say `#if __cpp_lib_ssize`, for example, to test whether the
- * compiler supports `std::ssize_t`.  If it doesn't, then the macro will not
- * exist, and the `#if` decides that no, you don't have that feature.  But
- * some users may ask their compilers to report any use of an undefined macro
- * as an error.
- *
- * So, we define alternate macros here that you can safely use in `#if`.
- */
-#if defined(__cpp_multidimensional_subscript)
-#  if __cpp_multidimensional_subscript
-#    define pqxx_have_multidim 1
-#  endif // __cpp_multidimensional_subscript
-#endif   // __cpp_multidimensional_subscript
-#if !defined(pqxx_have_multidim)
-#  define pqxx_have_multidim 0
-#endif // pqxx_have_multidim
-
-#if defined(__cpp_lib_source_location) && __cpp_lib_source_location
-#  define pqxx_have_source_location 1
-#else
-#  define pqxx_have_source_location 0
-#endif // __cpp_lib_source_location
-
-#if defined(__cpp_lib_ssize) && __cpp_lib_ssize
-#  define pqxx_have_ssize 1
-#else
-#  define pqxx_have_ssize 0
-#endif // __cpp_lib_ssize
-
-#if defined(__cpp_lib_unreachable) && __cpp_lib_unreachable
-#  define pqxx_have_unreachable 1
-#else
-#  define pqxx_have_unreachable 0
-#endif // __cpp_lib_unreachable