diff --git a/rpc/block_writer.go b/rpc/block_writer.go
index 949b1e5f..a8bd7c43 100644
--- a/rpc/block_writer.go
+++ b/rpc/block_writer.go
@@ -110,7 +110,13 @@ func (bw *BlockWriter) Close() error {
 func (bw *BlockWriter) connectNext() error {
 	address := getDatanodeAddress(bw.currentPipeline()[0])
 
-	conn, err := net.DialTimeout("tcp", address, connectTimeout)
+	var conn net.Conn
+	var err error
+	if bw.namenode.BlockWriterDialTimeout != nil {
+		conn, err = bw.namenode.BlockWriterDialTimeout("tcp", address, connectTimeout)
+	} else {
+		conn, err = net.DialTimeout("tcp", address, connectTimeout)
+	}
 	if err != nil {
 		return err
 	}
diff --git a/rpc/namenode.go b/rpc/namenode.go
index 15a1184e..45768880 100644
--- a/rpc/namenode.go
+++ b/rpc/namenode.go
@@ -7,6 +7,7 @@ import (
 	"io"
 	"net"
 	"sync"
+	"time"
 
 	hadoop "github.com/colinmarc/hdfs/protocol/hadoop_common"
 	"github.com/golang/protobuf/proto"
@@ -23,12 +24,13 @@ const (
 
 // NamenodeConnection represents an open connection to a namenode.
 type NamenodeConnection struct {
-	clientId         []byte
-	clientName       string
-	currentRequestID int
-	user             string
-	conn             net.Conn
-	reqLock          sync.Mutex
+	clientId               []byte
+	clientName             string
+	currentRequestID       int
+	user                   string
+	conn                   net.Conn
+	reqLock                sync.Mutex
+	BlockWriterDialTimeout func(network, address string, timeout time.Duration) (net.Conn, error)
 }
 
 // NamenodeError represents an interepreted error from the Namenode, including