--- include/X11/Xutil.h
+++ include/X11/Xutil.h
@@ -250,7 +250,7 @@
 #define IsModifierKey(keysym) \
   ((((KeySym)(keysym) >= XK_Shift_L) && ((KeySym)(keysym) <= XK_Hyper_R)) \
    || (((KeySym)(keysym) >= XK_ISO_Lock) && \
-       ((KeySym)(keysym) <= XK_ISO_Last_Group_Lock)) \
+       ((KeySym)(keysym) <= XK_ISO_Level5_Lock)) \
    || ((KeySym)(keysym) == XK_Mode_switch) \
    || ((KeySym)(keysym) == XK_Num_Lock))
 #else