diff --git a/core/icon.js b/core/icon.js
index b6b8942a7..69ff3ef37 100644
--- a/core/icon.js
+++ b/core/icon.js
@@ -53,6 +53,7 @@ Icon.prototype.collapseHidden = true;
 
 /**
  * Height and width of icons.
+ * @const
  */
 Icon.prototype.SIZE = 17;