diff --git a/src/node/onoff-application.cc b/src/node/onoff-application.cc
index a62b9d639..a4f00621d 100644
--- a/src/node/onoff-application.cc
+++ b/src/node/onoff-application.cc
@@ -60,7 +60,7 @@ uint32_t OnOffApplication::g_defaultSize = 512;
       m_cbrRate(rate),
       m_pktSize(size), 
       m_residualBits(0),
-      m_lastStartTime(0),
+      m_lastStartTime((HighPrecision)0),
       m_maxBytes(0xffffffff),
       m_totBytes(0),
       m_startStopScheduled(false),
diff --git a/src/simulator/nstime.h b/src/simulator/nstime.h
index 464fe58ce..cfa07f0eb 100644
--- a/src/simulator/nstime.h
+++ b/src/simulator/nstime.h
@@ -308,6 +308,21 @@ class TimeUnit<1>
   // -*- New methods -*-
 public:
 
+  /**
+   * \brief String constructor
+   * Construct TimeUnit<1> object from common time expressions like "
+   * 1ms" or "10s".  Supported units include:
+   * - s  (seconds)
+   * - ms (milliseconds)
+   * - us (microseconds)
+   * - ns (nanoseconds)
+   *
+   * There can be no white space between the numerical portion
+   * and the units.  Any otherwise malformed string causes a fatal error to
+   * occur.
+   * \param s The string to parse into a TimeUnit<1>
+   */
+  TimeUnit<1>(const std::string& s);
   /**
    * \returns an approximation in seconds of the time stored in this
    *          instance.
diff --git a/src/simulator/time.cc b/src/simulator/time.cc
index 7ad27c48b..184e57c99 100644
--- a/src/simulator/time.cc
+++ b/src/simulator/time.cc
@@ -20,9 +20,43 @@
  */
 #include "time.h"
 #include "simulator.h"
+#include "ns3/fatal-error.h"
 
 namespace ns3 {
 
+TimeUnit<1>::TimeUnit(const std::string& s)
+{
+  std::string::size_type n = s.find_first_not_of("0123456789.");
+  if (n != std::string::npos)
+  { // Found non-numeric
+    double r = atof(s.substr(0, n).c_str());
+    std::string trailer = s.substr(n, std::string::npos);
+    if (trailer == std::string("s"))
+    {
+      m_data = HighPrecision (r * 1000000000.0);
+      return;
+    }
+    if (trailer == std::string("ms"))
+    {
+      m_data = HighPrecision ((int64_t)(r * 1000000), false);
+      return;
+    }
+    if (trailer == std::string("us"))
+    {
+      m_data = HighPrecision ((int64_t)(r * 1000), false);
+      return;
+    }
+    if (trailer == std::string("ns"))
+    {
+      m_data = HighPrecision ((int64_t)r, false);
+      return;
+    }
+    NS_FATAL_ERROR("Can't Parse Time "<<s);
+  }
+  //else
+  //they didn't provide units, assume seconds
+  m_data = HighPrecision (atof(s.c_str()) * 1000000000.0);
+}
 double 
 TimeUnit<1>::GetSeconds (void) const
 {