diff --git a/README b/README
index 7218fad..c7368c6 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-This is UIPEthernet version 1.58
+This is UIPEthernet version 1.59
 
 An plugin-replacement of the stock Arduino Ethernet library for ENC28J60 shields and breakout boards. Full support for persistent (streaming) TCP-connections and UDP (Client and Server each), ARP, ICMP, DHCP and DNS. 
 Just include 'UIPEthernet.h' instead of 'Ethernet.h' and use all your code written for the stock Arduino Ethernet lib!
@@ -28,7 +28,7 @@ On a Mac, you will want to create a folder named "libraries" in in the "Document
     
 Or you download the zipped version of the library from https://github.com/ntruchsess/arduino_uip/releases, and copy the contained directory UIPEthernet to [path to Arduino distribution]\libraries\UIPEthernet.
 
-If you are running Arduino-IDE 1.5.x use release-version 1.57 or checkout branch 'Arduino_1.5.5'
+If you are running Arduino-IDE 1.5.x use release-version 1.59 or checkout branch 'Arduino_1.5.x'
 
 Additional information can be found on the Arduino website: http://www.arduino.cc/en/Hacking/Libraries
 
diff --git a/UIPEthernet/src/UIPClient.cpp b/UIPEthernet/src/UIPClient.cpp
index 21ddd79..d199cfe 100644
--- a/UIPEthernet/src/UIPClient.cpp
+++ b/UIPEthernet/src/UIPClient.cpp
@@ -329,6 +329,7 @@ UIPClient::flush()
 void
 uipclient_appcall(void)
 {
+  uint16_t send_len = 0;
   uip_userdata_t *u = (uip_userdata_t*)uip_conn->appstate;
   if (!u && uip_connected())
     {
@@ -360,17 +361,16 @@ uipclient_appcall(void)
 #endif
           if (uip_len && !(u->state & (UIP_CLIENT_CLOSE | UIP_CLIENT_REMOTECLOSED)))
             {
-              memhandle newPacket = Enc28J60Network::allocBlock(uip_len);
-              if (newPacket != NOBLOCK)
+              for (uint8_t i=0; i < UIP_SOCKET_NUMPACKETS; i++)
                 {
-                  for (uint8_t i=0; i < UIP_SOCKET_NUMPACKETS; i++)
+                  if (u->packets_in[i] == NOBLOCK)
                     {
-                      if (u->packets_in[i] == NOBLOCK)
+                      u->packets_in[i] = Enc28J60Network::allocBlock(uip_len);
+                      if (u->packets_in[i] != NOBLOCK)
                         {
+                          Enc28J60Network::copyPacket(u->packets_in[i],0,UIPEthernetClass::in_packet,((uint8_t*)uip_appdata)-uip_buf,uip_len);
                           if (i == UIP_SOCKET_NUMPACKETS-1)
                             uip_stop();
-                          Enc28J60Network::copyPacket(newPacket,0,UIPEthernetClass::in_packet,((uint8_t*)uip_appdata)-uip_buf,uip_len);
-                          u->packets_in[i] = newPacket;
                           goto finish_newdata;
                         }
                     }
@@ -407,7 +407,7 @@ uipclient_appcall(void)
           UIPClient::_dumpAllData();
 #endif
           uip_conn->appstate = NULL;
-          goto nodata;
+          goto finish;
         }
       if (uip_acked())
         {
@@ -425,26 +425,25 @@ uipclient_appcall(void)
             {
               if (u->packets_out[1] == NOBLOCK)
                 {
-                  uip_len = u->out_pos;
-                  if (uip_len > 0)
+                  send_len = u->out_pos;
+                  if (send_len > 0)
                     {
-                      Enc28J60Network::resizeBlock(u->packets_out[0],0,uip_len);
+                      Enc28J60Network::resizeBlock(u->packets_out[0],0,send_len);
                     }
                 }
               else
-                uip_len = Enc28J60Network::blockSize(u->packets_out[0]);
-              if (uip_len > 0)
+                send_len = Enc28J60Network::blockSize(u->packets_out[0]);
+              if (send_len > 0)
                 {
                   UIPEthernetClass::uip_hdrlen = ((uint8_t*)uip_appdata)-uip_buf;
-                  UIPEthernetClass::uip_packet = Enc28J60Network::allocBlock(UIPEthernetClass::uip_hdrlen+uip_len);
+                  UIPEthernetClass::uip_packet = Enc28J60Network::allocBlock(UIPEthernetClass::uip_hdrlen+send_len);
                   if (UIPEthernetClass::uip_packet != NOBLOCK)
                     {
-                      Enc28J60Network::copyPacket(UIPEthernetClass::uip_packet,UIPEthernetClass::uip_hdrlen,u->packets_out[0],0,uip_len);
+                      Enc28J60Network::copyPacket(UIPEthernetClass::uip_packet,UIPEthernetClass::uip_hdrlen,u->packets_out[0],0,send_len);
                       UIPEthernetClass::packetstate |= UIPETHERNET_SENDPACKET;
-                      uip_send(uip_appdata,uip_len);
                     }
-                  return;
                 }
+              goto finish;
             }
         }
       // don't close connection unless all outgoing packets are sent
@@ -473,9 +472,9 @@ uipclient_appcall(void)
             }
         }
     }
-nodata:
-  UIPEthernetClass::uip_packet = NOBLOCK;
-  uip_len=0;
+  finish:
+  uip_send(uip_appdata,send_len);
+  uip_len = send_len;
 }
 
 uip_userdata_t *
diff --git a/UIPEthernet/src/UIPEthernet.cpp b/UIPEthernet/src/UIPEthernet.cpp
index cf7d67c..91ec70a 100644
--- a/UIPEthernet/src/UIPEthernet.cpp
+++ b/UIPEthernet/src/UIPEthernet.cpp
@@ -183,7 +183,7 @@ UIPEthernetClass::tick()
           Enc28J60Network::readPacket(in_packet,0,(uint8_t*)uip_buf,UIP_BUFSIZE);
           if (ETH_HDR ->type == HTONS(UIP_ETHTYPE_IP))
             {
-              uip_packet = in_packet;
+              uip_packet = in_packet; //required for upper_layer_checksum of in_packet!
 #ifdef UIPETHERNET_DEBUG
               Serial.print(F("readPacket type IP, uip_len: "));
               Serial.println(uip_len);
@@ -220,7 +220,7 @@ UIPEthernetClass::tick()
         }
     }
 
-unsigned long now = millis();
+  unsigned long now = millis();
 
 #if UIP_CLIENT_TIMER >= 0
   boolean periodic = (long)( now - periodic_timer ) >= 0;
@@ -291,6 +291,7 @@ boolean UIPEthernetClass::network_send()
       Serial.println(uip_hdrlen);
 #endif
       Enc28J60Network::writePacket(uip_packet,0,uip_buf,uip_hdrlen);
+      packetstate &= ~ UIPETHERNET_SENDPACKET;
       goto sendandfree;
     }
   uip_packet = Enc28J60Network::allocBlock(uip_len);
diff --git a/UIPEthernet/src/utility/Enc28J60Network.cpp b/UIPEthernet/src/utility/Enc28J60Network.cpp
index 2e5febc..9c154cd 100644
--- a/UIPEthernet/src/utility/Enc28J60Network.cpp
+++ b/UIPEthernet/src/utility/Enc28J60Network.cpp
@@ -243,8 +243,6 @@ Enc28J60Network::blockSize(memhandle handle)
 void
 Enc28J60Network::sendPacket(memhandle handle)
 {
-  if (handle == NOBLOCK)
-    return;
   memblock *packet = &blocks[handle];
   uint16_t start = packet->begin-1;
   uint16_t end = start + packet->size;