diff --git a/tutorial/08-tutorial.lisp b/tutorial/08-tutorial.lisp
index 169aec9..9c61f0b 100644
--- a/tutorial/08-tutorial.lisp
+++ b/tutorial/08-tutorial.lisp
@@ -12,7 +12,7 @@
    (in-drag
     :accessor in-drag-p
     :initform nil
-    :documentation "Insure only one box is dragged at a time.")
+    :documentation "Ensure only one box is dragged at a time.")
    (drag-x
     :accessor drag-x
     :documentation "The location of the left side of the box relative to mouse during drag.")