diff --git a/riscos/thumbnail.c b/riscos/thumbnail.c
index ed240fd28..2cb357ac5 100644
--- a/riscos/thumbnail.c
+++ b/riscos/thumbnail.c
@@ -63,7 +63,7 @@ static void thumbnail_restore_output(struct thumbnail_save_area *save_area);
  *
  * \param  content  content structure to thumbnail
  * \param  bitmap   the bitmap to draw to
- * \param  url      the URL the thumnail belongs to, or NULL
+ * \param  url      the URL the thumbnail belongs to, or NULL
  */
 bool thumbnail_create(struct content *content, struct bitmap *bitmap,
 		const char *url)