--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -82,9 +82,7 @@
   *
   * Changing this requires an initdb.
   */
-#if SIZEOF_VOID_P >= 8
-#define USE_FLOAT8_BYVAL 1
-#endif
+#undef USE_FLOAT8_BYVAL

  /*
   * When we don't have native spinlocks, we use semaphores to simulate