diff --git a/contrib/gdtoa/gdtoaimp.h b/contrib/gdtoa/gdtoaimp.h
index 76a1ea2c2f36..105a657e968f 100644
--- a/contrib/gdtoa/gdtoaimp.h
+++ b/contrib/gdtoa/gdtoaimp.h
@@ -203,6 +203,7 @@ extern Char *MALLOC ANSI((size_t));
 #endif
 
 #define INFNAN_CHECK
+#define USE_LOCALE
 
 #undef IEEE_Arith
 #undef Avoid_Underflow