diff --git a/transport/control.go b/transport/control.go
index 0ffccdf4..63810953 100644
--- a/transport/control.go
+++ b/transport/control.go
@@ -35,7 +35,9 @@ package transport
 
 import (
 	"fmt"
+	"math"
 	"sync"
+	"time"
 
 	"golang.org/x/net/http2"
 )
@@ -44,18 +46,16 @@ const (
 	// The default value of flow control window size in HTTP2 spec.
 	defaultWindowSize = 65535
 	// The initial window size for flow control.
-	initialWindowSize     = defaultWindowSize      // for an RPC
-	initialConnWindowSize = defaultWindowSize * 16 // for a connection
+	initialWindowSize       = defaultWindowSize      // for an RPC
+	initialConnWindowSize   = defaultWindowSize * 16 // for a connection
+	defaultKeepaliveTime    = time.Duration(math.MaxInt64)
+	defaultKeepaliveTimeout = time.Duration(20 * time.Second)
 )
 
 // The following defines various control items which could flow through
 // the control buffer of transport. They represent different aspects of
 // control tasks, e.g., flow control, settings, streaming resetting, etc.
 
-type resetKeepaliveTimer struct{}
-
-func (resetKeepaliveTimer) item() {}
-
 type windowUpdate struct {
 	streamID  uint32
 	increment uint32
diff --git a/transport/transport.go b/transport/transport.go
index fb0df6d4..81a4f6de 100644
--- a/transport/transport.go
+++ b/transport/transport.go
@@ -41,10 +41,8 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"math"
 	"net"
 	"sync"
-	"time"
 
 	"golang.org/x/net/context"
 	"google.golang.org/grpc/codes"
@@ -611,10 +609,3 @@ func wait(ctx context.Context, done, goAway, closing <-chan struct{}, proceed <-
 		return i, nil
 	}
 }
-
-// keepalive related constants.
-const (
-	infinity                = time.Duration(math.MaxInt64)
-	defaultKeepaliveTime    = infinity
-	defaultKeepaliveTimeout = time.Duration(20 * time.Second)
-)