diff --git a/extra/nehe/4/4.factor b/extra/nehe/4/4.factor
index 10217c93cb..fda22d2f1e 100644
--- a/extra/nehe/4/4.factor
+++ b/extra/nehe/4/4.factor
@@ -7,7 +7,7 @@ TUPLE: nehe4-gadget < gadget rtri rquad thread quit? ;
 
 : width 256 ;
 : height 256 ;
-: redraw-interval 10 milliseconds ;
+: redraw-interval ( -- dt ) 10 milliseconds ;
 
 : <nehe4-gadget> (  -- gadget )
   nehe4-gadget new-gadget
diff --git a/extra/nehe/5/5.factor b/extra/nehe/5/5.factor
index 2c9b51c63f..30d0991fd8 100755
--- a/extra/nehe/5/5.factor
+++ b/extra/nehe/5/5.factor
@@ -6,7 +6,7 @@ IN: nehe.5
 TUPLE: nehe5-gadget < gadget rtri rquad thread quit? ;
 : width 256 ;
 : height 256 ;
-: redraw-interval 10 milliseconds ;
+: redraw-interval ( -- dt ) 10 milliseconds ;
 
 : <nehe5-gadget> (  -- gadget )
   nehe5-gadget new-gadget