* src/base/fttrigon.c (ft_trig_prenorm): Comment on undefined behavior.
diff --git a/src/base/fttrigon.c b/src/base/fttrigon.c
index 4ffdcb7..e3ce8a6 100644
--- a/src/base/fttrigon.c
+++ b/src/base/fttrigon.c
@@ -111,6 +111,7 @@
#endif /* !FT_LONG64 */
+ /* undefined and never called for zero vector */
static FT_Int
ft_trig_prenorm( FT_Vector* vec )
{