--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -2028,19 +2028,18 @@ error:
      * If we try to use the context without a selected compartment,
      * we will crash.
      */
     compartment = NULL;
 }
 
 /*
  * Since this function is only called in the context of a pending exception,
- * the caller must subsequently take an error path. If wrapping fails, we leave
- * the exception cleared, which, in the context of an error path, will be
- * interpreted as an uncatchable exception.
+ * the caller must subsequently take an error path. If wrapping fails, it will
+ * set a new (uncatchable) exception to be used in place of the original.
  */
 void
 JSContext::wrapPendingException()
 {
     Value v = getPendingException();
     clearPendingException();
     if (compartment->wrap(this, &v))
         setPendingException(v);