diff --git a/hw/xwin/winkeybd.h b/hw/xwin/winkeybd.h
index 4e4c35c37..5135e9ced 100644
--- a/hw/xwin/winkeybd.h
+++ b/hw/xwin/winkeybd.h
@@ -35,6 +35,8 @@
  */
 #include "winkeynames.h"
 
+#define VK_FN 0xFF
+
 #define		WIN_KEYMAP_COLS		3
 
 /* Rows 160 through 165 correspond to software-generated codes, which
@@ -298,7 +300,7 @@ g_iKeyMap [] = {
   /* 252 */	0,		0,		0,
   /* 253 */	0,		0,		0,
   /* 254 */	0,		0,		0,
-  /* 255 */	0,		0,		0
+  /* 255 */	VK_FN,		0,		KEY_Fn  /* Most keyboards don't generate a scancode for Fn, but a few do... */
 };
 
 #endif /* WINKEYBD_H */
diff --git a/hw/xwin/winkeynames.h b/hw/xwin/winkeynames.h
index 914016a76..75e172e1f 100644
--- a/hw/xwin/winkeynames.h
+++ b/hw/xwin/winkeynames.h
@@ -144,7 +144,7 @@
 #define KEY_KP_0         /* 0           Insert    0x52  */   82
 #define KEY_KP_Decimal   /* . (Decimal) Delete    0x53  */   83 
 #define KEY_SysReqest    /* SysReqest             0x54  */   84
-                         /* NOTUSED               0x55  */
+#define KEY_Fn           /* Fn                    0x55  */   85
 #define KEY_Less         /* < (Less)   >(Greater) 0x56  */   86
 #define KEY_F11          /* F11                   0x57  */   87
 #define KEY_F12          /* F12                   0x58  */   88