diff --git a/stdlib-sup39/draw.sun b/stdlib-sup39/draw.sun
index 93ce631..d98c429 100644
--- a/stdlib-sup39/draw.sun
+++ b/stdlib-sup39/draw.sun
@@ -13,7 +13,8 @@ builtin setMTX(dst, ...);
 var const MTX_LOADIMM = 0;
 var const MTX_NEW = 0;
 
-builtin drawRect(fill, stroke, x0, y0, x1, y1);
+// drawRect(fill, stroke, x0, y0, x1, y1, resetMtx=true)
+builtin drawRect(fill, stroke, x0, y0, x1, y1, ...);
 var const FILL_NONE = 0;
 var const STROKE_NONE = 0;