diff --git a/input/keycodes.h b/input/keycodes.h
index 53fb682e46..1326df6902 100644
--- a/input/keycodes.h
+++ b/input/keycodes.h
@@ -210,8 +210,13 @@
 #define MP_AXIS_LEFT      (MP_AXIS_BASE+2)
 #define MP_AXIS_RIGHT     (MP_AXIS_BASE+3)
 
+// Reserved area. Can be used for keys that have no explicit names assigned,
+// but should be mappable by the user anyway.
+#define MP_KEY_UNKNOWN_RESERVED_START (MP_KEY_BASE+0x10000)
+#define MP_KEY_UNKNOWN_RESERVED_LAST (MP_KEY_BASE+0x20000-1)
+
 /* Special keys */
-#define MP_KEY_INTERN (MP_KEY_BASE+0x1000)
+#define MP_KEY_INTERN (MP_KEY_BASE+0x20000)
 #define MP_KEY_CLOSE_WIN (MP_KEY_INTERN+0)
 // Generated by input.c (VOs use mp_input_set_mouse_pos())
 #define MP_KEY_MOUSE_MOVE ((MP_KEY_INTERN+1)|MP_NO_REPEAT_KEY)
diff --git a/video/out/x11_common.c b/video/out/x11_common.c
index 0e02069ae6..1f933bfcae 100644
--- a/video/out/x11_common.c
+++ b/video/out/x11_common.c
@@ -611,6 +611,13 @@ static int vo_x11_lookupkey(int key)
     if (!mpkey)
         mpkey = lookup_keymap_table(keymap, key);
 
+    // XFree86 keysym range; typically contains obscure "extra" keys
+    if (!mpkey && key >= 0x10080001 && key <= 0x1008FFFF) {
+        mpkey = MP_KEY_UNKNOWN_RESERVED_START + (key - 0x10080000);
+        if (mpkey > MP_KEY_UNKNOWN_RESERVED_LAST)
+            mpkey = 0;
+    }
+
     return mpkey;
 }