diff --git a/src/ISO8601.cpp b/src/ISO8601.cpp
index 85813a4d3..797828ab8 100644
--- a/src/ISO8601.cpp
+++ b/src/ISO8601.cpp
@@ -1243,6 +1243,20 @@ void ISO8601d::operator++ ()
   _date = tomorrow._date;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// Postfix increment by one day.
+void ISO8601d::operator++ (int)
+{
+  ISO8601d tomorrow = (startOfDay () + 90001).startOfDay ();
+  tomorrow = ISO8601d (tomorrow.month (),
+                       tomorrow.day (),
+                       tomorrow.year (),
+                       hour (),
+                       minute (),
+                       second ());
+  _date = tomorrow._date;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void ISO8601p::clear ()
 {
diff --git a/src/ISO8601.h b/src/ISO8601.h
index 0694a149c..f5fbc1e9c 100644
--- a/src/ISO8601.h
+++ b/src/ISO8601.h
@@ -88,6 +88,7 @@ public:
   void operator-- ();    // Prefix
   void operator-- (int); // Postfix
   void operator++ ();    // Prefix
+  void operator++ (int); // Postfix
 
 private:
   void clear ();