diff --git a/src/RTClib.cpp b/src/RTClib.cpp
index 8f1f4ea5..4fdd8c40 100644
--- a/src/RTClib.cpp
+++ b/src/RTClib.cpp
@@ -130,6 +130,13 @@ static uint32_t time2ulong(uint16_t days, uint8_t h, uint8_t m, uint8_t s) {
   return ((days * 24UL + h) * 60 + m) * 60 + s;
 }
 
+/**************************************************************************/
+/*!
+    @brief  Default constructor.
+*/
+/**************************************************************************/
+DateTime::DateTime() : yOff(0), m(1), d(1), hh(0), mm(0), ss(0) {}
+
 /**************************************************************************/
 /*!
     @brief  Constructor from
@@ -710,6 +717,13 @@ String DateTime::timestamp(timestampOpt opt) const {
   return String(buffer);
 }
 
+/**************************************************************************/
+/*!
+    @brief  Default constructor.
+*/
+/**************************************************************************/
+TimeSpan::TimeSpan() : _seconds(0) {}
+
 /**************************************************************************/
 /*!
     @brief  Create a new TimeSpan object in seconds
diff --git a/src/RTClib.h b/src/RTClib.h
index 879bb3fa..17e60464 100644
--- a/src/RTClib.h
+++ b/src/RTClib.h
@@ -142,7 +142,8 @@ enum Pcf8563SqwPinMode {
 /**************************************************************************/
 class DateTime {
 public:
-  DateTime(uint32_t t = SECONDS_FROM_1970_TO_2000);
+  DateTime();
+  DateTime(uint32_t t);
   DateTime(uint16_t year, uint8_t month, uint8_t day, uint8_t hour = 0,
            uint8_t min = 0, uint8_t sec = 0);
   DateTime(const DateTime &copy);
@@ -274,7 +275,8 @@ class DateTime {
 /**************************************************************************/
 class TimeSpan {
 public:
-  TimeSpan(int32_t seconds = 0);
+  TimeSpan();
+  TimeSpan(int32_t seconds);
   TimeSpan(int16_t days, int8_t hours, int8_t minutes, int8_t seconds);
   TimeSpan(const TimeSpan &copy);