diff --git a/src/tpdate2.hpp b/src/tpdate2.hpp
index 12ac573..75e38bd 100644
--- a/src/tpdate2.hpp
+++ b/src/tpdate2.hpp
@@ -30,6 +30,18 @@ class TwoPartDate2 {
   using FDOUBLE = /*long*/ double;
   int _mjd;      /** Mjd */
   FDOUBLE _fday; /** fractional part of day */
+  
+  /** Construct from MJD and fractional days.
+   *
+   * This is only private and should be used in rare cases. Normal users,
+   * should explicitely cast the second argument to FractionalSeconds or 
+   * FractionalDays to avoid misconceptions (i.e. is the parameters fractional 
+   * seconds or fractional days?).
+   */
+  explicit TwoPartDate2(int mjd, FDOUBLE fday) noexcept
+      : _mjd(mjd), _fday(fday) {
+    normalize();
+  }
 
 public:
   /** Constructor from datetime<T> */