diff --git a/lib/xy.h b/lib/xy.h
index f7bf3e3..faffad0 100644
--- a/lib/xy.h
+++ b/lib/xy.h
@@ -64,7 +64,6 @@ bool xy_on_macos = false;
 bool xy_on_bsd = false;
 bool xy_on_android = false;
 
-char *xy_os_devnull = NULL;
 
 /* 全局变量 与 全局状态 */
 struct
@@ -1222,9 +1221,9 @@ xy_init ()
   xy_detect_os ();
 
   if (xy_on_windows)
-    xy_os_devnull = "nul";
+    xy.os_devnull = "nul";
   else
-    xy_os_devnull = "/dev/null";
+    xy.os_devnull = "/dev/null";
 
   xy_use_utf8 ();
 }
diff --git a/src/framework/core.c b/src/framework/core.c
index c4f5486..35a024a 100644
--- a/src/framework/core.c
+++ b/src/framework/core.c
@@ -640,7 +640,7 @@ measure_speed_for_url (void *url)
       ipv6 = "--ipv6";
     }
 
-  char *os_devnull = xy_os_devnull;
+  char *os_devnull = xy.os_devnull;
 
   /**
    * @note 我们用 —L，因为部分链接会跳转到其他地方，比如: RubyChina, npmmirror