diff --git a/ui.h b/ui.h
index 05aa671f..8f598af0 100644
--- a/ui.h
+++ b/ui.h
@@ -383,6 +383,7 @@ _UI_EXTERN void uiDrawPathNewFigureWithArc(uiDrawPath *p, double xCenter, double
 _UI_EXTERN void uiDrawPathLineTo(uiDrawPath *p, double x, double y);
 // notes: angles are both relative to 0 and go counterclockwise
 // TODO is the initial line segment on cairo and OS X a proper join?
+// TODO what if sweep < 0?
 _UI_EXTERN void uiDrawPathArcTo(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep);
 _UI_EXTERN void uiDrawPathBezierTo(uiDrawPath *p, double c1x, double c1y, double c2x, double c2y, double endX, double endY);
 // TODO quadratic bezier