diff --git a/src/core/model/nstime.h b/src/core/model/nstime.h
index c0e977d78..e2998bfd0 100644
--- a/src/core/model/nstime.h
+++ b/src/core/model/nstime.h
@@ -530,7 +530,7 @@ public:
 
 
   /** Cast to int64x64_t */
-  inline operator int64x64_t () const
+  explicit inline operator int64x64_t () const
   {
     return int64x64_t (m_data);
   }
diff --git a/src/internet/test/ipv4-deduplication-test.cc b/src/internet/test/ipv4-deduplication-test.cc
index 0dcfdab78..922ae512a 100644
--- a/src/internet/test/ipv4-deduplication-test.cc
+++ b/src/internet/test/ipv4-deduplication-test.cc
@@ -609,7 +609,8 @@ Ipv4DeduplicationPerformanceTest::DoRun (void)
 
   for (uint8_t i = 0; i<nodes.GetN (); i++)
     {
-      Simulator::ScheduleWithContext (m_sockets[i]->GetNode ()->GetId (), Seconds (4+Seconds(jitter->GetValue ())),
+      Simulator::ScheduleWithContext (m_sockets[i]->GetNode ()->GetId (),
+                                      Seconds (4+jitter->GetValue ()),
                                       &Ipv4DeduplicationPerformanceTest::DoSendData, this, m_sockets[i], to, i);
     }
 
diff --git a/src/lr-wpan/model/lr-wpan-mac.cc b/src/lr-wpan/model/lr-wpan-mac.cc
index ecc4e8166..772ffe57d 100644
--- a/src/lr-wpan/model/lr-wpan-mac.cc
+++ b/src/lr-wpan/model/lr-wpan-mac.cc
@@ -449,8 +449,8 @@ LrWpanMac::McpsDataRequest (McpsDataRequestParams params, Ptr<Packet> p)
 
           //TODO:  check possible incorrect expire time here.
 
-          expireTime = MicroSeconds (Simulator::Now () + m_macTransactionPersistanceTime *
-                                     unitPeriodSymbols * 1000 * 1000 / m_phy->GetDataOrSymbolRate (false));
+          expireTime = Simulator::Now () + m_macTransactionPersistanceTime
+            * MicroSeconds (unitPeriodSymbols * 1000 * 1000 / m_phy->GetDataOrSymbolRate (false));
           indTxQElement->expireTime = expireTime;
           indTxQElement->txQMsduHandle = params.m_msduHandle;
           indTxQElement->txQPkt = p;
diff --git a/src/lr-wpan/model/lr-wpan-phy.h b/src/lr-wpan/model/lr-wpan-phy.h
index 9c34e6abf..5690daf51 100644
--- a/src/lr-wpan/model/lr-wpan-phy.h
+++ b/src/lr-wpan/model/lr-wpan-phy.h
@@ -432,6 +432,7 @@ public:
 
   /**
    * implement PLME SetAttribute confirm SAP
+   * bit rate is in kbit/s.  Symbol rate is in ksymbol/s.
    * @param isData is true for data rate or false for symbol rate
    * @return the rate value of this PHY
    */
@@ -492,7 +493,8 @@ public:
 protected:
   /**
    * The data and symbol rates for the different PHY options.
-   * See Table 2 in section 6.1.2 IEEE 802.15.4-2006
+   * See Table 2 in section 6.1.2 IEEE 802.15.4-2006.
+   * Bit rate is in kbit/s.  Symbol rate is in ksymbol/s.
    */
   static const LrWpanPhyDataAndSymbolRates dataSymbolRates[7];
   /**
diff --git a/src/traffic-control/test/codel-queue-disc-test-suite.cc b/src/traffic-control/test/codel-queue-disc-test-suite.cc
index ac7e8eb9d..2e8054b9d 100644
--- a/src/traffic-control/test/codel-queue-disc-test-suite.cc
+++ b/src/traffic-control/test/codel-queue-disc-test-suite.cc
@@ -970,7 +970,7 @@ CoDelQueueDiscBasicMark::Dequeue (Ptr<CoDelQueueDisc> queue, uint32_t modeSize,
                                         "There should be 1 CE threshold exceeded marked packet");
                 }
             }
-          else if (initialCeThreshMarkCount > 0 && currentTime.GetMicroSeconds () < queue->GetInterval ())
+          else if (initialCeThreshMarkCount > 0 && currentTime < queue->GetInterval ())
             { 
               if (initialCeThreshMarkCount < 2)
                 {
diff --git a/src/uan/model/uan-mac-rc.cc b/src/uan/model/uan-mac-rc.cc
index 0b503ea90..f658b5bde 100644
--- a/src/uan/model/uan-mac-rc.cc
+++ b/src/uan/model/uan-mac-rc.cc
@@ -366,7 +366,7 @@ UanMacRc::ReceiveOkFromPhy (Ptr<Packet> pkt, double sinr, UanTxMode mode)
 
         Time winDelay = ctsg.GetWindowTime ();
 
-        if (winDelay > 0)
+        if (winDelay > Time (0))
           {
             m_rtsBlocked = false;
             Simulator::Schedule (winDelay, &UanMacRc::BlockRtsing, this);
@@ -481,16 +481,9 @@ UanMacRc::ScheduleData (const UanHeaderRcCts &ctsh, const UanHeaderRcCtsGlobal &
 
       pkt->AddHeader (ch);
       Time eventTime = startDelay + frameDelay;
-      if (eventTime < 0)
+      if (eventTime < Time (0))
         {
-          if (eventTime > -0.001)
-            {
-              eventTime = Time ();
-            }
-          else
-            {
-              NS_FATAL_ERROR ("Scheduling error resulted in very negative data transmission time! eventTime = " << eventTime.As (Time::S));
-            }
+          NS_FATAL_ERROR ("Scheduling error resulted in very negative data transmission time! eventTime = " << eventTime.As (Time::S));
         }
       NS_LOG_DEBUG (Now ().As (Time::S) << 
                     " Node " << Mac8Address::ConvertFrom (GetAddress ()) <<