diff --git a/src/eval.c b/src/eval.c
index 6bd2aa7..c076560 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -11453,7 +11453,7 @@
 #if defined(UNIX) && (defined(__CYGWIN32__) || defined(__CYGWIN__))
 	"win32unix",
 #endif
-#ifdef WIN64
+#if defined(WIN64) || defined(_WIN64)
 	"win64",
 #endif
 #ifdef EBCDIC