diff --git a/R/fit.R b/R/fit.R
index e3c61baa..1b78068b 100644
--- a/R/fit.R
+++ b/R/fit.R
@@ -537,6 +537,8 @@ CmdStanFit$set("public", name = "unconstrain_variables", value = unconstrain_var
 #' @param files (character vector) The paths to the CmdStan CSV files. These can
 #'   be files generated by running CmdStanR or running CmdStan directly.
 #' @param draws A `posterior::draws_*` object.
+#' @param format (string) The format of the returned draws. Must be a valid
+#'   format from the \pkg{posterior} package.
 #'
 #' @examples
 #' \dontrun{
diff --git a/man/fit-method-unconstrain_draws.Rd b/man/fit-method-unconstrain_draws.Rd
index 2e6dd699..a4d96fc4 100644
--- a/man/fit-method-unconstrain_draws.Rd
+++ b/man/fit-method-unconstrain_draws.Rd
@@ -5,13 +5,16 @@
 \alias{unconstrain_draws}
 \title{Transform all parameter draws to the unconstrained scale}
 \usage{
-unconstrain_draws(files = NULL, draws = NULL)
+unconstrain_draws(files = NULL, draws = NULL, format = "draws_df")
 }
 \arguments{
 \item{files}{(character vector) The paths to the CmdStan CSV files. These can
 be files generated by running CmdStanR or running CmdStan directly.}
 
 \item{draws}{A \verb{posterior::draws_*} object.}
+
+\item{format}{(string) The format of the returned draws. Must be a valid
+format from the \pkg{posterior} package.}
 }
 \description{
 The \verb{$unconstrain_draws()} method transforms all parameter draws