diff --git a/src/libiso8601/400_c_library.h b/src/libiso8601/400_c_library.h
index 1a75cd0..f7abd38 100644
--- a/src/libiso8601/400_c_library.h
+++ b/src/libiso8601/400_c_library.h
@@ -19,8 +19,8 @@ conversion).
 
 /*! \brief Retrieve the current time.
 
-\param[out] date Current date/time (may be 0), in UTC.
-\param[out] details Details (may be 0), including timezone.
+\param[out] date Current date/time (may be 0), in UTC. May be 0.
+\param[out] details Details (may be 0), including timezone. May be 0.
 
 Retrieves the current time from the system clock, storing it into \a date and
 \a details (both parameters optional).