diff --git a/frame_sorter.go b/frame_sorter.go
index f0d3c9c85c3..5632536505d 100644
--- a/frame_sorter.go
+++ b/frame_sorter.go
@@ -2,6 +2,7 @@ package quic
 
 import (
 	"errors"
+
 	"github.com/lucas-clemente/quic-go/internal/utils/tree"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
diff --git a/frame_sorter_test.go b/frame_sorter_test.go
index de23f3a5d39..3fcdc7cfe7b 100644
--- a/frame_sorter_test.go
+++ b/frame_sorter_test.go
@@ -3,11 +3,12 @@ package quic
 import (
 	"bytes"
 	"fmt"
-	"github.com/lucas-clemente/quic-go/internal/utils/tree"
 	"math"
 	"math/rand"
 	"time"
 
+	"github.com/lucas-clemente/quic-go/internal/utils/tree"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils"
 	. "github.com/onsi/ginkgo"
diff --git a/internal/utils/streamframe_interval.go b/internal/utils/streamframe_interval.go
index fbe3ad4456e..b52e61d8d0b 100644
--- a/internal/utils/streamframe_interval.go
+++ b/internal/utils/streamframe_interval.go
@@ -2,6 +2,7 @@ package utils
 
 import (
 	"fmt"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
 	"github.com/lucas-clemente/quic-go/internal/utils/tree"
 )
diff --git a/internal/utils/tree/tree.go b/internal/utils/tree/tree.go
index 72780a6f7b3..54ff10c435b 100644
--- a/internal/utils/tree/tree.go
+++ b/internal/utils/tree/tree.go
@@ -50,13 +50,6 @@ func (t *Btree) NotEmpty() bool {
 	return t.root != nil
 }
 
-func (t *Btree) balance() int8 {
-	if t.root != nil {
-		return balance(t.root)
-	}
-	return 0
-}
-
 // Insert inserts a new value into the tree and returns the tree pointer
 func (t *Btree) Insert(value Val) *Btree {
 	added := false
@@ -170,7 +163,7 @@ func (t *Btree) Head() Val {
 	if t.root == nil {
 		return nil
 	}
-	var beginning = t.root
+	beginning := t.root
 	for beginning.left != nil {
 		beginning = beginning.left
 	}
@@ -190,7 +183,7 @@ func (t *Btree) Tail() Val {
 	if t.root == nil {
 		return nil
 	}
-	var beginning = t.root
+	beginning := t.root
 	for beginning.right != nil {
 		beginning = beginning.right
 	}
@@ -265,7 +258,7 @@ func deleteNode(n *Node, value Val, deleted *bool) *Node {
 		*deleted = true
 	}
 
-	//re-balance
+	// re-balance
 	if n == nil {
 		return n
 	}