diff --git a/src/gui_w32.c b/src/gui_w32.c
index 3c3d994..12d6071 100644
--- a/src/gui_w32.c
+++ b/src/gui_w32.c
@@ -1813,7 +1813,7 @@
 
 #ifdef FEAT_MBYTE
 /*
- * Convert latin9 text to ucs-2.
+ * Convert latin9 text "text[len]" to ucs-2 in "unicodebuf".
  */
     static void
 latin9_to_ucs(char_u *text, int len, WCHAR *unicodebuf)