diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index 3d2383c..b3cff9e 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -1,61 +1,63 @@
+---
 name: Benchmark
 
-on:
-- pull_request
+"on":
+  - pull_request
 
 jobs:
   benchmark:
     strategy:
       matrix:
         ref:
-        - master
-        - ${{ github.sha }}
+          - master
+          - ${{ github.sha }}
 
     runs-on: ubuntu-latest
 
     steps:
-    - name: Steup Go
-      uses: actions/setup-go@v2
-      with:
-        go-version: 1.17
-
-    - name: Checkout
-      uses: actions/checkout@v2
-      with:
-        ref: ${{ matrix.ref }}
-
-    - name: Run Benchmarks
-      run: go test -v -run '^$' -bench '(Marshal|Unmarshal)$/codeResponse' -benchmem -benchtime 3s -cpu 1 -count 5 ./json | tee bench.txt
-
-    - name: Upload Benchmarks
-      uses: actions/upload-artifact@v2
-      with:
-        name: ${{ matrix.ref }}
-        path: bench.txt
+      - name: Steup Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: "1.21"
+
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          ref: ${{ matrix.ref }}
+
+      - name: Run Benchmarks
+        # Without 6 iterations, benchstat will claim statistical insignificance.
+        run: go test -v -run '^$' -bench '(Marshal|Unmarshal)$/codeResponse' -benchmem -benchtime 3s -cpu 1 -count 6 ./json | tee bench.txt
+
+      - name: Upload Benchmarks
+        uses: actions/upload-artifact@v2
+        with:
+          name: ${{ matrix.ref }}
+          path: bench.txt
 
   benchstat:
     needs: [benchmark]
     runs-on: ubuntu-latest
 
     steps:
-    - name: Steup Go
-      uses: actions/setup-go@v2
-      with:
-        go-version: 1.17
-
-    - name: Setup Benchstat
-      run: go install golang.org/x/perf/cmd/benchstat@latest
-
-    - name: Download Benchmark Results
-      uses: actions/download-artifact@v2
-      with:
-        path: .
-
-    - name: Run Benchstat
-      run: benchstat ./master/bench.txt ./${{ github.sha }}/bench.txt | tee benchstat.txt
-
-    - name: Upload Benchstat Results
-      uses: actions/upload-artifact@v2
-      with:
-        name: benchstat
-        path: benchstat.txt
+      - name: Steup Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: "1.21"
+
+      - name: Setup Benchstat
+        run: go install golang.org/x/perf/cmd/benchstat@latest
+
+      - name: Download Benchmark Results
+        uses: actions/download-artifact@v2
+        with:
+          path: .
+
+      - name: Run Benchstat
+        run: benchstat ./master/bench.txt ./${{ github.sha }}/bench.txt | tee benchstat.txt
+
+      - name: Upload Benchstat Results
+        uses: actions/upload-artifact@v2
+        with:
+          name: benchstat
+          path: benchstat.txt
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 16acc54..7e4bc41 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,30 +1,29 @@
+---
 name: Test
 
-on:
-- pull_request
+"on":
+  - pull_request
 
 jobs:
   test:
     strategy:
       matrix:
         go:
-        - 1.14
-        - 1.15
-        - 1.16
-        - 1.17
+          - "1.20"
+          - "1.21"
 
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
+      - uses: actions/checkout@v2
 
-    - name: Setup Go ${{ matrix.go }}
-      uses: actions/setup-go@v2
-      with:
-        go-version: ${{ matrix.go }}
+      - name: Setup Go ${{ matrix.go }}
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go }}
 
-    - name: Download Dependencies
-      run: go mod download
+      - name: Download Dependencies
+        run: go mod download
 
-    - name: Run Tests
-      run: make test
+      - name: Run Tests
+        run: make test
diff --git a/Makefile b/Makefile
index ffb1396..4640625 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 .PHONY: test bench-simple clean update-golang-test fuzz fuzz-json
 
-golang.version ?= 1.15.2
+golang.version ?= 1.21
 golang.tmp.root := /tmp/golang$(golang.version)
 golang.tmp.json.root := $(golang.tmp.root)/go-go$(golang.version)/src/encoding/json
 golang.test.files := $(wildcard json/golang_*_test.go)
@@ -10,7 +10,7 @@ go-fuzz-build := ${GOPATH}/bin/go-fuzz-build
 go-fuzz-corpus := ${GOPATH}/src/github.com/dvyukov/go-fuzz-corpus
 go-fuzz-dep := ${GOPATH}/src/github.com/dvyukov/go-fuzz/go-fuzz-dep
 
-test: test-ascii test-json test-json-bugs test-json-1.17 test-proto test-iso8601 test-thrift test-purego
+test: test-ascii test-json test-json-bugs test-proto test-iso8601 test-thrift test-purego
 
 test-ascii:
 	go test -cover -race ./ascii
@@ -21,9 +21,6 @@ test-json:
 test-json-bugs:
 	go test -race ./json/bugs/...
 
-test-json-1.17:
-	go test -cover -race -tags go1.17 ./json
-
 test-proto:
 	go test -cover -race ./proto
 
diff --git a/json/golang_bench_test.go b/json/golang_bench_test.go
index 07cc378..04c9176 100644
--- a/json/golang_bench_test.go
+++ b/json/golang_bench_test.go
@@ -14,7 +14,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"reflect"
 	"runtime"
@@ -51,7 +51,7 @@ func codeInit() {
 	if err != nil {
 		panic(err)
 	}
-	data, err := ioutil.ReadAll(gz)
+	data, err := io.ReadAll(gz)
 	if err != nil {
 		panic(err)
 	}
@@ -88,7 +88,7 @@ func BenchmarkCodeEncoder(b *testing.B) {
 		b.StartTimer()
 	}
 	b.RunParallel(func(pb *testing.PB) {
-		enc := NewEncoder(ioutil.Discard)
+		enc := NewEncoder(io.Discard)
 		for pb.Next() {
 			if err := enc.Encode(&codeStruct); err != nil {
 				b.Fatal("Encode:", err)
diff --git a/proto/fixtures/generate/main.go b/proto/fixtures/generate/main.go
index 3016afd..0614934 100644
--- a/proto/fixtures/generate/main.go
+++ b/proto/fixtures/generate/main.go
@@ -1,7 +1,6 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 
 	"github.com/golang/protobuf/proto"
@@ -28,6 +27,6 @@ func main() {
 
 	for _, test := range tests {
 		b, _ := proto.Marshal(&test.value)
-		ioutil.WriteFile("protobuf/"+test.name, b, 0644)
+		os.WriteFile("protobuf/"+test.name, b, 0644)
 	}
 }
diff --git a/proto/proto_test.go b/proto/proto_test.go
index fd7573a..d978aaf 100644
--- a/proto/proto_test.go
+++ b/proto/proto_test.go
@@ -3,8 +3,8 @@ package proto
 import (
 	"encoding/binary"
 	"fmt"
-	"io/ioutil"
 	"math"
+	"os"
 	"reflect"
 	"testing"
 )
@@ -366,7 +366,7 @@ func TestMarshalUnmarshal(t *testing.T) {
 }
 
 func loadProtobuf(t *testing.T, fileName string) RawMessage {
-	b, err := ioutil.ReadFile("fixtures/protobuf/" + fileName)
+	b, err := os.ReadFile("fixtures/protobuf/" + fileName)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/thrift/decode.go b/thrift/decode.go
index 341d10a..4cc394b 100644
--- a/thrift/decode.go
+++ b/thrift/decode.go
@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"reflect"
 	"sync/atomic"
 )
@@ -656,7 +655,7 @@ func skipBinary(r Reader) error {
 	case *bufio.Reader:
 		_, err = x.Discard(int(n))
 	default:
-		_, err = io.CopyN(ioutil.Discard, x, int64(n))
+		_, err = io.CopyN(io.Discard, x, int64(n))
 	}
 	return dontExpectEOF(err)
 }