diff --git a/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/FrameParser.java b/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/FrameParser.java
index 38760f8..e3b3c55 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/FrameParser.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/FrameParser.java
@@ -94,7 +94,7 @@
         _frameHandler = frameHandler;
         _decoder = decoder;
         _localMaxFrameSize = localMaxFrameSize;
-        _inputBufferSize = _localMaxFrameSize > 0 ? _localMaxFrameSize : 4*1024;
+        _inputBufferSize = _localMaxFrameSize > 0 ? _localMaxFrameSize : 16*1024;
     }
 
     private void input(ByteBuffer in) throws TransportException
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/TransportOutputAdaptor.java b/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/TransportOutputAdaptor.java
index c427a9a..f43d7e0 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/TransportOutputAdaptor.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/engine/impl/TransportOutputAdaptor.java
@@ -40,7 +40,7 @@
     TransportOutputAdaptor(TransportOutputWriter transportOutputWriter, int maxFrameSize, boolean readOnlyHead)
     {
         _transportOutputWriter = transportOutputWriter;
-        _maxFrameSize = maxFrameSize > 0 ? maxFrameSize : 4*1024;
+        _maxFrameSize = maxFrameSize > 0 ? maxFrameSize : 16*1024;
         _readOnlyHead = readOnlyHead;
     }