Merge pull request #202 from tromey/note-prep-cif-var-usage document that there must be ntotalargs types
diff --git a/doc/libffi.texi b/doc/libffi.texi
index 054fdb7..ff72e58 100644
--- a/doc/libffi.texi
+++ b/doc/libffi.texi
@@ -161,7 +161,7 @@ same as for @code{ffi_prep_cif} except that:
variadic arguments. It must be greater than zero.
@var{ntotalargs} the total number of arguments, including variadic
-and fixed arguments.
+and fixed arguments. @var{argtypes} must have this many elements.
Note that, different cif's must be prepped for calls to the same
function when different numbers of arguments are passed.