diff --git a/src/ncp/ncp_buffer.cpp b/src/ncp/ncp_buffer.cpp
index 8293797c2..49ef17578 100644
--- a/src/ncp/ncp_buffer.cpp
+++ b/src/ncp/ncp_buffer.cpp
@@ -71,6 +71,7 @@ void NcpFrameBuffer::Clear(void)
     mWriteFrameTag = kInvalidTag;
 
     // Read (OutFrame) related variables
+    mReadDirection = kForward;
     mReadState = kReadStateNotActive;
     mReadFrameLength = kUnknownFrameLength;