Fix comment.
diff --git a/src/sfnt/ttpost.c b/src/sfnt/ttpost.c
index f140649..6de99ef 100644
--- a/src/sfnt/ttpost.c
+++ b/src/sfnt/ttpost.c
@@ -473,8 +473,8 @@
/* idx :: The glyph index. */
/* */
/* <InOut> */
- /* PSname :: The address of a string pointer. Will be NULL in case */
- /* of error, otherwise it is a pointer to the glyph name. */
+ /* PSname :: The address of a string pointer. Undefined in case of */
+ /* error, otherwise it is a pointer to the glyph name. */
/* */
/* You must not modify the returned string! */
/* */