diff --git a/keysymdef.h b/keysymdef.h
index d504e5c..84b4683 100644
--- a/keysymdef.h
+++ b/keysymdef.h
@@ -385,6 +385,7 @@ SOFTWARE.
 #define XK_dead_acute                    0xfe51
 #define XK_dead_circumflex               0xfe52
 #define XK_dead_tilde                    0xfe53
+#define XK_dead_perispomeni              0xfe53  /* alias for dead_tilde */
 #define XK_dead_macron                   0xfe54
 #define XK_dead_breve                    0xfe55
 #define XK_dead_abovedot                 0xfe56