diff --git a/src/share/classes/java/util/Formatter.java b/src/share/classes/java/util/Formatter.java
index f5f479588c1175d75f249d22597d1aaa2334c216..03a58004918a874f4d5ba5b666c6a08eb962373c 100644
--- a/src/share/classes/java/util/Formatter.java
+++ b/src/share/classes/java/util/Formatter.java
@@ -351,7 +351,9 @@ import sun.misc.FormattedFloatingDecimal;
  * <tr><td valign="top">{@code 'a'}, {@code 'A'}
  *     <td valign="top"> floating point
  *     <td> The result is formatted as a hexadecimal floating-point number with
- *     a significand and an exponent
+ *     a significand and an exponent. This conversion is <b>not</b> supported
+ *     for the {@code BigDecimal} type despite the latter's being in the
+ *     <i>floating point</i> argument category.
  *
  * <tr><td valign="top">{@code 't'}, {@code 'T'}
  *     <td valign="top"> date/time