diff --git a/build.gradle b/build.gradle
index 7a8e3ab..3d5ba79 100644
--- a/build.gradle
+++ b/build.gradle
@@ -3,7 +3,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.2.0'
+        classpath 'com.android.tools.build:gradle:2.2.3'
     }
 }
 
diff --git a/usbserial/src/main/java/com/felhr/usbserial/SerialBuffer.java b/usbserial/src/main/java/com/felhr/usbserial/SerialBuffer.java
index 1e7bb2b..a59f53e 100644
--- a/usbserial/src/main/java/com/felhr/usbserial/SerialBuffer.java
+++ b/usbserial/src/main/java/com/felhr/usbserial/SerialBuffer.java
@@ -118,6 +118,7 @@ public class SerialBuffer
 
         public synchronized void put(byte[] src)
         {
+            if(src == null || src.length == 0) return;
             if(position == -1)
                 position = 0;
             if(debugging)
@@ -148,6 +149,7 @@ public class SerialBuffer
                     e.printStackTrace();
                 }
             }
+            if(position <= -1 ) return new byte[0];
             byte[] dst =  Arrays.copyOfRange(buffer, 0, position);
             if(debugging)
                 UsbSerialDebugger.printLogGet(dst, true);
diff --git a/usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java b/usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java
index 1b37a88..95b7594 100644
--- a/usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java
+++ b/usbserial/src/main/java/com/felhr/usbserial/UsbSerialDevice.java
@@ -304,7 +304,8 @@ public abstract class UsbSerialDevice implements UsbSerialInterface
             while(working.get())
             {
                 byte[] data = serialBuffer.getWriteBuffer();
-                connection.bulkTransfer(outEndpoint, data, data.length, USB_TIMEOUT);
+                if(data.length > 0)
+                    connection.bulkTransfer(outEndpoint, data, data.length, USB_TIMEOUT);
             }
         }
 
diff --git a/usbserial/src/main/java/com/felhr/usbserial/UsbSpiDevice.java b/usbserial/src/main/java/com/felhr/usbserial/UsbSpiDevice.java
index c9c8425..b831aa8 100644
--- a/usbserial/src/main/java/com/felhr/usbserial/UsbSpiDevice.java
+++ b/usbserial/src/main/java/com/felhr/usbserial/UsbSpiDevice.java
@@ -99,7 +99,8 @@ public abstract class UsbSpiDevice implements UsbSpiInterface
             while(working.get())
             {
                 byte[] data = serialBuffer.getWriteBuffer();
-                connection.bulkTransfer(outEndpoint, data, data.length, USB_TIMEOUT);
+                if(data.length > 0)
+                    connection.bulkTransfer(outEndpoint, data, data.length, USB_TIMEOUT);
             }
         }