diff --git a/NEWS.md b/NEWS.md
index 222229f34..afb220b1f 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -19,6 +19,7 @@
  * Whitespace is not trimmed when rendering tables with `as_html`.
  * Started deprecation cycle for `col_fnotes_here` to be replaced with `col_footnotes`.
  * Exported `section_div` methods now have a dedicated documentation page that is visible to users.
+ * When tables are exported as `txt`, they preserve the horizontal separator of the table.
 
 ## rtables 0.6.5
 ### New Features
diff --git a/R/argument_conventions.R b/R/argument_conventions.R
index 70c6cd964..bcc7c1bd5 100644
--- a/R/argument_conventions.R
+++ b/R/argument_conventions.R
@@ -53,7 +53,8 @@ NULL
 #' @param hsep character(1). Set of character(s) to be repeated as the separator
 #'   between the header and body of the table when rendered as text. Defaults to
 #'   a connected horizontal line (unicode 2014) in locals that use a UTF
-#'   charset, and to `-` elsewhere (with a once per session warning).
+#'   charset, and to `-` elsewhere (with a once per session warning). See 
+#'   [formatters::set_default_hsep()] for further information.
 #' @param indent_size numeric(1). Number of spaces to use per indent level.
 #'   Defaults to 2
 #' @param section_div character(1). String which should be repeated as a section
diff --git a/R/tt_toString.R b/R/tt_toString.R
index bbbcd6987..2f46d5510 100644
--- a/R/tt_toString.R
+++ b/R/tt_toString.R
@@ -19,12 +19,9 @@ NULL
 
 #' Convert an `rtable` object to a string
 #'
+#' @inheritParams formatters::toString
 #' @inheritParams gen_args
 #' @inherit formatters::toString
-#' @param x table object
-#' @param widths widths of row.name and columns
-#' @param col_gap gap between columns
-#' @param hsep character to create line separator
 #' @exportMethod toString
 #'
 #' @return a string representation of \code{x} as it appears when printed.
@@ -340,6 +337,7 @@ setMethod(
       prov_footer = prov_footer(obj),
       table_inset = table_inset(obj),
       header_section_div = header_section_div(obj),
+      horizontal_sep = horizontal_sep(obj),
       indent_size = indent_size
     )
   }
diff --git a/man/build_table.Rd b/man/build_table.Rd
index 3e1cc9528..353a35a4d 100644
--- a/man/build_table.Rd
+++ b/man/build_table.Rd
@@ -38,7 +38,8 @@ displayed during printing.}
 \item{hsep}{character(1). Set of character(s) to be repeated as the separator
 between the header and body of the table when rendered as text. Defaults to
 a connected horizontal line (unicode 2014) in locals that use a UTF
-charset, and to \code{-} elsewhere (with a once per session warning).}
+charset, and to \code{-} elsewhere (with a once per session warning). See
+\code{\link[formatters:default_horizontal_sep]{formatters::set_default_hsep()}} for further information.}
 
 \item{\dots}{currently ignored.}
 }
diff --git a/man/export_as_pdf.Rd b/man/export_as_pdf.Rd
index 7af03060a..df34fc3c8 100644
--- a/man/export_as_pdf.Rd
+++ b/man/export_as_pdf.Rd
@@ -78,7 +78,9 @@ this is calculated automatically based on the specified page
 size). \code{NULL} indicates no horizontal pagination should occur.}
 
 \item{hsep}{character(1). Characters to repeat to create
-header/body separator line.}
+header/body separator line. If \code{NULL}, the object value will be
+used. If \code{" "}, an empty separator will be printed. Check \code{\link[formatters:default_hsep]{default_hsep()}}
+for more information.}
 
 \item{indent_size}{numeric(1). Indent size in characters. Ignored
 when \code{x} is already a \code{MatrixPrintForm} object in favor of information
@@ -87,9 +89,9 @@ there.}
 \item{tf_wrap}{logical(1). Should  the texts for  title, subtitle,
 and footnotes be wrapped?}
 
-\item{max_width}{integer(1), character(1) or NULL. Width that title
+\item{max_width}{integer(1), character(1) or \code{NULL}. Width that title
 and   footer   (including   footnotes)  materials   should   be
-word-wrapped to. If NULL, it is  set to the current print width
+word-wrapped to. If \code{NULL}, it is  set to the current print width
 of the  session (\code{getOption("width")}). If set to \code{"auto"},
 the width of the table (plus any table inset) is used. Ignored
 completely if \code{tf_wrap} is \code{FALSE}.}
diff --git a/man/gen_args.Rd b/man/gen_args.Rd
index 53ce36782..a965d0de3 100644
--- a/man/gen_args.Rd
+++ b/man/gen_args.Rd
@@ -89,7 +89,8 @@ when forcing pagination between the children of this split/table}
 \item{hsep}{character(1). Set of character(s) to be repeated as the separator
 between the header and body of the table when rendered as text. Defaults to
 a connected horizontal line (unicode 2014) in locals that use a UTF
-charset, and to \code{-} elsewhere (with a once per session warning).}
+charset, and to \code{-} elsewhere (with a once per session warning). See
+\code{\link[formatters:default_horizontal_sep]{formatters::set_default_hsep()}} for further information.}
 
 \item{indent_size}{numeric(1). Number of spaces to use per indent level.
 Defaults to 2}
diff --git a/man/paginate.Rd b/man/paginate.Rd
index c4bd27c4b..92bed8aed 100644
--- a/man/paginate.Rd
+++ b/man/paginate.Rd
@@ -49,9 +49,9 @@ considerations. Defaults to none.}
 
 \item{colwidths}{numeric vector. Column widths for use with vertical pagination.}
 
-\item{max_width}{integer(1), character(1) or NULL. Width that title
+\item{max_width}{integer(1), character(1) or \code{NULL}. Width that title
 and   footer   (including   footnotes)  materials   should   be
-word-wrapped to. If NULL, it is  set to the current print width
+word-wrapped to. If \code{NULL}, it is  set to the current print width
 of the  session (\code{getOption("width")}). If set to \code{"auto"},
 the width of the table (plus any table inset) is used. Ignored
 completely if \code{tf_wrap} is \code{FALSE}.}
diff --git a/man/rtable.Rd b/man/rtable.Rd
index 94c82b6e0..5a8e402ab 100644
--- a/man/rtable.Rd
+++ b/man/rtable.Rd
@@ -24,7 +24,8 @@ format labels.}
 \item{hsep}{character(1). Set of character(s) to be repeated as the separator
 between the header and body of the table when rendered as text. Defaults to
 a connected horizontal line (unicode 2014) in locals that use a UTF
-charset, and to \code{-} elsewhere (with a once per session warning).}
+charset, and to \code{-} elsewhere (with a once per session warning). See
+\code{\link[formatters:default_horizontal_sep]{formatters::set_default_hsep()}} for further information.}
 
 \item{inset}{integer(1). The table inset for the row or table being
 constructed. See \code{\link[formatters]{table_inset}}.}
diff --git a/man/tabclasses.Rd b/man/tabclasses.Rd
index 2c74806b8..69bd45993 100644
--- a/man/tabclasses.Rd
+++ b/man/tabclasses.Rd
@@ -117,7 +117,8 @@ tables that need a divider between them.}
 \item{hsep}{character(1). Set of character(s) to be repeated as the separator
 between the header and body of the table when rendered as text. Defaults to
 a connected horizontal line (unicode 2014) in locals that use a UTF
-charset, and to \code{-} elsewhere (with a once per session warning).}
+charset, and to \code{-} elsewhere (with a once per session warning). See
+\code{\link[formatters:default_horizontal_sep]{formatters::set_default_hsep()}} for further information.}
 
 \item{trailing_section_div}{character(1). String which will be used as a section
 divider after the printing of the last row contained in this (sub)-table,
diff --git a/man/table_shell.Rd b/man/table_shell.Rd
index 824266d7c..31fa94f06 100644
--- a/man/table_shell.Rd
+++ b/man/table_shell.Rd
@@ -27,18 +27,24 @@ table_shell_str(
 \item{tt}{\code{TableTree} (or related class). A \code{TableTree} object representing a
 populated table.}
 
-\item{widths}{widths of row.name and columns}
+\item{widths}{numeric (or  \code{NULL}). (proposed) widths for the columns
+of \code{x}. The expected length  of this numeric vector can be
+retrieved with  \code{ncol() + 1}  as the  column of row  names must
+also be considered.}
 
-\item{col_gap}{gap between columns}
+\item{col_gap}{numeric(1). Space (in characters) between columns}
 
-\item{hsep}{character to create line separator}
+\item{hsep}{character(1). Characters to repeat to create
+header/body separator line. If \code{NULL}, the object value will be
+used. If \code{" "}, an empty separator will be printed. Check \code{\link[formatters:default_hsep]{default_hsep()}}
+for more information.}
 
 \item{tf_wrap}{logical(1). Should  the texts for  title, subtitle,
 and footnotes be wrapped?}
 
-\item{max_width}{integer(1), character(1) or NULL. Width that title
+\item{max_width}{integer(1), character(1) or \code{NULL}. Width that title
 and   footer   (including   footnotes)  materials   should   be
-word-wrapped to. If NULL, it is  set to the current print width
+word-wrapped to. If \code{NULL}, it is  set to the current print width
 of the  session (\code{getOption("width")}). If set to \code{"auto"},
 the width of the table (plus any table inset) is used. Ignored
 completely if \code{tf_wrap} is \code{FALSE}.}
diff --git a/man/tostring.Rd b/man/tostring.Rd
index 00fb3e691..05903fbc1 100644
--- a/man/tostring.Rd
+++ b/man/tostring.Rd
@@ -16,13 +16,19 @@
 )
 }
 \arguments{
-\item{x}{table object}
+\item{x}{ANY. Object to be prepared for rendering.}
 
-\item{widths}{widths of row.name and columns}
+\item{widths}{numeric (or  \code{NULL}). (proposed) widths for the columns
+of \code{x}. The expected length  of this numeric vector can be
+retrieved with  \code{ncol() + 1}  as the  column of row  names must
+also be considered.}
 
-\item{col_gap}{gap between columns}
+\item{col_gap}{numeric(1). Space (in characters) between columns}
 
-\item{hsep}{character to create line separator}
+\item{hsep}{character(1). Characters to repeat to create
+header/body separator line. If \code{NULL}, the object value will be
+used. If \code{" "}, an empty separator will be printed. Check \code{\link[formatters:default_hsep]{default_hsep()}}
+for more information.}
 
 \item{indent_size}{numeric(1). Number of spaces to use per indent level.
 Defaults to 2}
@@ -30,9 +36,9 @@ Defaults to 2}
 \item{tf_wrap}{logical(1). Should  the texts for  title, subtitle,
 and footnotes be wrapped?}
 
-\item{max_width}{integer(1), character(1) or NULL. Width that title
+\item{max_width}{integer(1), character(1) or \code{NULL}. Width that title
 and   footer   (including   footnotes)  materials   should   be
-word-wrapped to. If NULL, it is  set to the current print width
+word-wrapped to. If \code{NULL}, it is  set to the current print width
 of the  session (\code{getOption("width")}). If set to \code{"auto"},
 the width of the table (plus any table inset) is used. Ignored
 completely if \code{tf_wrap} is \code{FALSE}.}
diff --git a/man/tt_to_flextable.Rd b/man/tt_to_flextable.Rd
index 64ecd92a6..8befa8e87 100644
--- a/man/tt_to_flextable.Rd
+++ b/man/tt_to_flextable.Rd
@@ -81,9 +81,9 @@ regardless of page size.}
 \item{tf_wrap}{logical(1). Should  the texts for  title, subtitle,
 and footnotes be wrapped?}
 
-\item{max_width}{integer(1), character(1) or NULL. Width that title
+\item{max_width}{integer(1), character(1) or \code{NULL}. Width that title
 and   footer   (including   footnotes)  materials   should   be
-word-wrapped to. If NULL, it is  set to the current print width
+word-wrapped to. If \code{NULL}, it is  set to the current print width
 of the  session (\code{getOption("width")}). If set to \code{"auto"},
 the width of the table (plus any table inset) is used. Ignored
 completely if \code{tf_wrap} is \code{FALSE}.}
diff --git a/tests/testthat/test-printing.R b/tests/testthat/test-printing.R
index e944e1553..0ab5f8dd0 100644
--- a/tests/testthat/test-printing.R
+++ b/tests/testthat/test-printing.R
@@ -739,3 +739,20 @@ test_that("Separators and wrapping work together with getter and setters", {
     "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
   )
 })
+
+test_that("horizontal separator is propagated from table to print and export", {
+  # GitHub error #778
+  lyt <- basic_table() %>%
+    split_cols_by("Species") %>%
+    analyze("Sepal.Length", afun = function(x) {
+      list(
+        "mean (sd)" = rcell(c(mean(x), sd(x)), format = "xx.xx (xx.xx)"),
+        "range" = diff(range(x))
+      )
+    })
+  
+  tbl <- build_table(lyt, iris, hsep = "~")
+  tostring_tbl <- strsplit(toString(tbl), "\n")[[1]]
+  export_txt_tbl <- strsplit(export_as_txt(tbl), "\n")[[1]]
+  expect_identical(tostring_tbl, export_txt_tbl)
+})