diff --git a/HISTORY.md b/HISTORY.md
index 6afccd5..48bb633 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -1,3 +1,7 @@
+# UNRELEASED
+
+  * return NaN when not a number
+
 # 0.2.3 (2014-08-23)
 
   * fix parsing scientific notation numbers