diff --git a/R/converters.R b/R/converters.R
index d8128aaa3..72b3bb7c6 100644
--- a/R/converters.R
+++ b/R/converters.R
@@ -94,6 +94,9 @@ calc_col_width <- function(base_font, col_width) {
   font <- base_font$name$val
   size <- as.integer(base_font$size$val)
 
+  if (!any(font %in% font_width_tab$FontFamilyName))
+    font <- "Aptos Narrow"
+
   sel <- font_width_tab$FontFamilyName == font & font_width_tab$FontSize == size
   # maximum digit width of selected font
   mdw <- font_width_tab$Width[sel]
diff --git a/tests/testthat/test-converters.R b/tests/testthat/test-converters.R
index f23b8e686..dadfc2f1b 100644
--- a/tests/testthat/test-converters.R
+++ b/tests/testthat/test-converters.R
@@ -58,3 +58,10 @@ test_that("", {
   expect_equal(got, 8)
 
 })
+
+test_that("unknown font works", {
+  wb <- wb_workbook()
+  wb$add_worksheet("Sheet 1")
+  wb$set_base_font(font_name = "Roboto")
+  expect_silent(wb$set_col_widths(cols = c(1, 4, 6, 7, 9), widths = c(16, 15, 12, 18, 33)))
+})