diff --git a/R/derive_date_vars.R b/R/derive_date_vars.R
index 8d7569a7c5..41339f6427 100644
--- a/R/derive_date_vars.R
+++ b/R/derive_date_vars.R
@@ -40,8 +40,9 @@
 #' date is not before the first treatment date. Only dates which are in the
 #' range of possible dates of the `dtc` value are considered. The possible dates
 #' are defined by the missing parts of the `dtc` date (see example below). This
-#' ensures that the non-missing parts of the `dtc` date are not changed. For
-#' example
+#' ensures that the non-missing parts of the `dtc` date are not changed.
+#' A date or date-time object is expected.
+#' For example
 #'
 #' ```
 #' impute_dtc(
@@ -64,7 +65,7 @@
 #' A list of dates is expected. It is ensured that the imputed date is not after
 #' any of the specified dates, e.g., that the imputed date is not after the data
 #' cut off date. Only dates which are in the range of possible dates are
-#' considered.
+#' considered. A date or date-time object is expected.
 #'
 #' @param preserve Preserve day if month is missing and day is present
 #'