diff --git a/src/ISO8601.cpp b/src/ISO8601.cpp
index d6c0e73e7..6fa9df6c1 100644
--- a/src/ISO8601.cpp
+++ b/src/ISO8601.cpp
@@ -840,6 +840,12 @@ bool ISO8601p::parse (const std::string& input, std::string::size_type& start)
   return false;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+ISO8601d ISO8601d::startOfDay () const
+{
+  return ISO8601d (month (), day (), year ());
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Static
 bool ISO8601d::leapYear (int year)
diff --git a/src/ISO8601.h b/src/ISO8601.h
index 559794f4e..d4cd49768 100644
--- a/src/ISO8601.h
+++ b/src/ISO8601.h
@@ -43,10 +43,11 @@ public:
   ISO8601d (const int, const int, const int, const int, const int, const int);
   ~ISO8601d ();
   ISO8601d (const ISO8601d&);                 // Unimplemented
-  ISO8601d& operator= (const ISO8601d&);      // Unimplemented
   operator time_t () const;
   bool parse (const std::string&, std::string::size_type&, const std::string& format = "");
 
+  ISO8601d startOfDay () const;
+
   static bool leapYear (int);
   static int daysInMonth (int, int);
   static int daysInYear (int);