diff --git a/platform/darwin/src/MGLShapeSource.h b/platform/darwin/src/MGLShapeSource.h
index 7d8a64595..a44db6947 100644
--- a/platform/darwin/src/MGLShapeSource.h
+++ b/platform/darwin/src/MGLShapeSource.h
@@ -192,6 +192,9 @@ extern const MGLShapeSourceOption MGLShapeSourceOptionSimplificationTolerance;
  If the receiver was initialized using `-initWithIdentifier:URL:options:`, this
  property is set to `nil`. This property is unavailable until the receiver is
  passed into `-[MGLStyle addSource:]`.
+ 
+ You can get/set the shapes within a collection via this property. Actions must 
+ be performed on the application's main thread.
  */
 @property (nonatomic, copy, nullable) MGLShape *shape;