diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 1c7e3cd2d0..e1aa7e8b23 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -128,7 +128,7 @@
 /* #undef HAVE_FP_CLASS_H */
 
 /* Define to 1 if fseeko (and presumably ftello) exists and is declared. */
-/* #undef HAVE_FSEEKO */
+#define HAVE_FSEEKO 1
 
 /* Define to 1 if your compiler understands __func__. */
 //#define HAVE_FUNCNAME__FUNC 1