diff --git a/app/scripts/config.js b/app/scripts/config.js
index 8b3d1bd..aa99156 100644
--- a/app/scripts/config.js
+++ b/app/scripts/config.js
@@ -303,6 +303,7 @@ function ConfigView() {
         <Grid item xs={8}>
           <TextField
             label="__MSG_blacklist__"
+            helperText='Both URLS and extensions are valid. For file extensions, only include the text of the extension itself (e.g. "pdf"). Entries should be their own lines.'
             multiline
             fullWidth
             rows={4}