diff --git a/src/gui_riscos.c b/src/gui_riscos.c
index 46e79c0..6adc8b7 100644
--- a/src/gui_riscos.c
+++ b/src/gui_riscos.c
@@ -2873,7 +2873,7 @@
 }
 
 /* Size of buffer has changed.
- * Add one to max since gui.c substracts one more than it should!
+ * Add one to max since gui.c subtracts one more than it should!
  */
     void
 gui_mch_set_scrollbar_thumb(sb, val, size, max)