diff --git a/scripts/render_html_list.R b/scripts/render_html_list.R
index 4aec2483..6a5de18a 100644
--- a/scripts/render_html_list.R
+++ b/scripts/render_html_list.R
@@ -7,11 +7,11 @@
 files <- readr::read_csv("lecture_files.csv", show_col_types = FALSE)
 
 if(nrow(files) > 0) {
-  files$files <- sapply(files$files, gsub, pattern = ".Rmd", replacement = "")
-  files$files <- sapply(files$files, gsub, pattern = "modules/.*/", replacement = "")
+  files$files <- stringr::str_replace_all(files$files, pattern = ".Rmd", replacement = "")
+  files$files <- stringr::str_replace_all(files$files, pattern = "modules/.*/", replacement = "")
   
   # Don't need to render HWs
-  files <- files[!grepl("homework", files)]
+  files <- files[!grepl("homework", files$files),]
 } else {
   # Just render the Intro files if no others to render.
   files <- data.frame(