diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index be32817c..811fc677 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -15,7 +15,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.16
+        go-version: 1.18
 
     - name: Test
       run: go test ./...
@@ -28,7 +28,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.16
+        go-version: 1.18
 
     - name: Test with race
       run: go test -race ./...
diff --git a/internal/locate/sorted_btree.go b/internal/locate/sorted_btree.go
index 933332e0..c72bed67 100644
--- a/internal/locate/sorted_btree.go
+++ b/internal/locate/sorted_btree.go
@@ -32,9 +32,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !go1.18
-// +build !go1.18
-
 package locate
 
 import (
@@ -43,31 +40,31 @@ import (
 	"github.com/google/btree"
 )
 
-// SortedRegionsRegions is a sorted btree.
+// SortedRegions is a sorted btree.
 type SortedRegions struct {
-	b *btree.BTree
+	b *btree.BTreeG[*btreeItem]
 }
 
 // NewSortedRegions returns a new SortedRegions.
 func NewSortedRegions(btreeDegree int) *SortedRegions {
 	return &SortedRegions{
-		b: btree.New(btreeDegree),
+		b: btree.NewG(btreeDegree, func(a, b *btreeItem) bool { return a.Less(b) }),
 	}
 }
 
 // ReplaceOrInsert inserts a new item into the btree.
 func (s *SortedRegions) ReplaceOrInsert(cachedRegion *Region) *Region {
-	old := s.b.ReplaceOrInsert(newBtreeItem(cachedRegion))
+	old, _ := s.b.ReplaceOrInsert(newBtreeItem(cachedRegion))
 	if old != nil {
-		return old.(*btreeItem).cachedRegion
+		return old.cachedRegion
 	}
 	return nil
 }
 
 // DescendLessOrEqual returns all items that are less than or equal to the key.
 func (s *SortedRegions) DescendLessOrEqual(key []byte, isEndKey bool, ts int64) (r *Region) {
-	s.b.DescendLessOrEqual(newBtreeSearchItem(key), func(item btree.Item) bool {
-		r = item.(*btreeItem).cachedRegion
+	s.b.DescendLessOrEqual(newBtreeSearchItem(key), func(item *btreeItem) bool {
+		r = item.cachedRegion
 		if isEndKey && bytes.Equal(r.StartKey(), key) {
 			r = nil     // clear result
 			return true // iterate next item
@@ -83,8 +80,8 @@ func (s *SortedRegions) DescendLessOrEqual(key []byte, isEndKey bool, ts int64)
 
 // AscendGreaterOrEqual returns all items that are greater than or equal to the key.
 func (s *SortedRegions) AscendGreaterOrEqual(startKey, endKey []byte, limit int) (regions []*Region) {
-	s.b.AscendGreaterOrEqual(newBtreeSearchItem(startKey), func(item btree.Item) bool {
-		region := item.(*btreeItem).cachedRegion
+	s.b.AscendGreaterOrEqual(newBtreeSearchItem(startKey), func(item *btreeItem) bool {
+		region := item.cachedRegion
 		if len(endKey) > 0 && bytes.Compare(region.StartKey(), endKey) >= 0 {
 			return false
 		}
@@ -101,8 +98,8 @@ func (s *SortedRegions) Clear() {
 
 // ValidRegionsInBtree returns the number of valid regions in the btree.
 func (s *SortedRegions) ValidRegionsInBtree(ts int64) (len int) {
-	s.b.Descend(func(item btree.Item) bool {
-		r := item.(*btreeItem).cachedRegion
+	s.b.Descend(func(item *btreeItem) bool {
+		r := item.cachedRegion
 		if !r.checkRegionCacheTTL(ts) {
 			return true
 		}
diff --git a/internal/locate/sorted_btree_generic.go b/internal/locate/sorted_btree_generic.go
deleted file mode 100644
index 02ca4cd5..00000000
--- a/internal/locate/sorted_btree_generic.go
+++ /dev/null
@@ -1,113 +0,0 @@
-// Copyright 2022 TiKV Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// NOTE: The code in this file is based on code from the
-// TiDB project, licensed under the Apache License v 2.0
-//
-// https://github.com/pingcap/tidb/tree/cc5e161ac06827589c4966674597c137cc9e809c/store/tikv/locate/region_request.go
-//
-
-// Copyright 2016 PingCAP, Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-//go:build go1.18
-// +build go1.18
-
-package locate
-
-import (
-	"bytes"
-
-	"github.com/google/btree"
-)
-
-// SortedRegions is a sorted btree.
-type SortedRegions struct {
-	b *btree.BTreeG[*btreeItem]
-}
-
-// NewSortedRegions returns a new SortedRegions.
-func NewSortedRegions(btreeDegree int) *SortedRegions {
-	return &SortedRegions{
-		b: btree.NewG(btreeDegree, func(a, b *btreeItem) bool { return a.Less(b) }),
-	}
-}
-
-// ReplaceOrInsert inserts a new item into the btree.
-func (s *SortedRegions) ReplaceOrInsert(cachedRegion *Region) *Region {
-	old, _ := s.b.ReplaceOrInsert(newBtreeItem(cachedRegion))
-	if old != nil {
-		return old.cachedRegion
-	}
-	return nil
-}
-
-// DescendLessOrEqual returns all items that are less than or equal to the key.
-func (s *SortedRegions) DescendLessOrEqual(key []byte, isEndKey bool, ts int64) (r *Region) {
-	s.b.DescendLessOrEqual(newBtreeSearchItem(key), func(item *btreeItem) bool {
-		r = item.cachedRegion
-		if isEndKey && bytes.Equal(r.StartKey(), key) {
-			r = nil     // clear result
-			return true // iterate next item
-		}
-		if !r.checkRegionCacheTTL(ts) {
-			r = nil
-			return true
-		}
-		return false
-	})
-	return r
-}
-
-// AscendGreaterOrEqual returns all items that are greater than or equal to the key.
-func (s *SortedRegions) AscendGreaterOrEqual(startKey, endKey []byte, limit int) (regions []*Region) {
-	s.b.AscendGreaterOrEqual(newBtreeSearchItem(startKey), func(item *btreeItem) bool {
-		region := item.cachedRegion
-		if len(endKey) > 0 && bytes.Compare(region.StartKey(), endKey) >= 0 {
-			return false
-		}
-		regions = append(regions, region)
-		return len(regions) < limit
-	})
-	return regions
-}
-
-// Clear removes all items from the btree.
-func (s *SortedRegions) Clear() {
-	s.b.Clear(false)
-}
-
-// ValidRegionsInBtree returns the number of valid regions in the btree.
-func (s *SortedRegions) ValidRegionsInBtree(ts int64) (len int) {
-	s.b.Descend(func(item *btreeItem) bool {
-		r := item.cachedRegion
-		if !r.checkRegionCacheTTL(ts) {
-			return true
-		}
-		len++
-		return true
-	})
-	return
-}