diff --git a/src/os_win32.h b/src/os_win32.h
index 8553910..a6ac891 100644
--- a/src/os_win32.h
+++ b/src/os_win32.h
@@ -78,6 +78,8 @@
 # define BREAKCHECK_SKIP    1	/* call mch_breakcheck() each time, it's fast */
 #endif
 
+#define HAVE_TOTAL_MEM
+
 #define HAVE_PUTENV		/* at least Bcc 5.2 and MSC have it */
 
 #ifdef FEAT_GUI_W32