diff --git a/src/ng/filter/filters.js b/src/ng/filter/filters.js
index fe49719ffa82..52845d042185 100644
--- a/src/ng/filter/filters.js
+++ b/src/ng/filter/filters.js
@@ -80,7 +80,7 @@ function currencyFilter($locale) {
  * @description
  * Formats a number as text.
  *
- * If the input is not a number an empty string is returned.
+ * If the input is not a number an empty string is returned but null or undefined, these values will be passed through.
  *
  * If the input is an infinite (Infinity/-Infinity) the Infinity symbol '∞' is returned.
  *