diff --git a/README.md b/README.md
index aaf74ec..cf3c551 100644
--- a/README.md
+++ b/README.md
@@ -187,6 +187,8 @@ t | Add triangle surface
 q | Add quad surface
 g | Add grid warp surface
 d | duplicate surface
++ | Scale surface up
+- | Scale surface down
 p | toggle perspective warping (quad surfaces only)
 ] | add columns to grid surface (grid warp surfaces only)
 [ | remove columns from grid surface (grid warp surfaces only)