diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index d764905..0d50075 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -18,7 +18,7 @@ jobs:
           - windows-latest
         go-version:
           - 1.x
-          - 1.13.x
+          - 1.16.x
     runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v2
@@ -53,7 +53,12 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
+      - uses: actions/setup-go@v1
+        with:
+          go-version: '1.16'
+
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v2
+        uses: golangci/golangci-lint-action@master
         with:
-          version: v1.35
+          version: v1.37
+          skip-go-installation: true
diff --git a/.golangci.yml b/.golangci.yml
index 5532d29..711bd70 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -7,14 +7,16 @@ issues:
 linters:
   enable-all: true
   disable:
-    - lll
+    - cyclop
+    - exhaustivestruct
+    - forbidigo
     - funlen
-    - gofumpt
     - gci
+    - gofumpt
+    - ifshort
+    - lll
     - nlreturn
-    - testpackage
-    - exhaustivestruct
-    - wrapcheck
     - paralleltest
-    - forbidigo
+    - testpackage
     - thelper
+    - wrapcheck
diff --git a/README.md b/README.md
index a5d8419..4f42159 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ asc-go is a Go client library for accessing Apple's [App Store Connect API](http
 
 ## Usage
 
-This project uses Go Modules.
+This project uses Go Modules. It requires **Go 1.16 or higher**.
 
 ```go
 import "github.com/cidertool/asc-go/asc"
@@ -35,6 +35,7 @@ You may find that the code snippet above will always fail due to a lack of autho
 
 ```go
 import (
+    "os"
     "time"
 
     "github.com/cidertool/asc-go/asc"
@@ -48,7 +49,7 @@ func main() {
     // A duration value for the lifetime of a token. App Store Connect does not accept a token with a lifetime of longer than 20 minutes
     expiryDuration = 20*time.Minute
     // The bytes of the PKCS#8 private key created on App Store Connect. Keep this key safe as you can only download it once.
-    privateKey = ioutil.ReadFile("path/to/key")
+    privateKey = os.ReadFile("path/to/key")
 
     auth, err = asc.NewTokenConfig(keyID, issuerID, expiryDuration, privateKey)
     if err != nil {
diff --git a/asc/asc.go b/asc/asc.go
index 4644c9c..ce57d52 100644
--- a/asc/asc.go
+++ b/asc/asc.go
@@ -26,7 +26,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httputil"
@@ -411,7 +410,7 @@ func checkResponse(r *Response) error {
 		return nil
 	}
 
-	data, err := ioutil.ReadAll(r.Body)
+	data, err := io.ReadAll(r.Body)
 	erro := new(ErrorResponse)
 
 	if err == nil && data != nil {
@@ -510,8 +509,7 @@ func (e ErrorResponseError) String(level int) string {
 
 // Close closes an open descriptor.
 func closeDesc(c io.Closer) {
-	err := c.Close()
-	if err != nil {
+	if err := c.Close(); err != nil {
 		log.Fatal(err)
 	}
 }
diff --git a/asc/asc_test.go b/asc/asc_test.go
index d928657..5bc05fa 100644
--- a/asc/asc_test.go
+++ b/asc/asc_test.go
@@ -24,7 +24,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -186,7 +186,7 @@ func TestCheckBadResponse(t *testing.T) {
 				Method: "GET",
 				URL:    &url.URL{},
 			},
-			Body: ioutil.NopCloser(strings.NewReader(`{
+			Body: io.NopCloser(strings.NewReader(`{
 				"errors": [
 				  	{
 						"code": "",
diff --git a/asc/doc.go b/asc/doc.go
index f339f5e..f454dae 100644
--- a/asc/doc.go
+++ b/asc/doc.go
@@ -51,6 +51,7 @@ and rotating JSON Web Tokens automatically. For example, the above snippet could
 to look a little more like this:
 
 	import (
+		"os"
 		"time"
 
 		"github.com/cidertool/asc-go/asc"
@@ -66,7 +67,7 @@ to look a little more like this:
 		expiryDuration = 20*time.Minute
 		// The bytes of the PKCS#8 private key created on App Store Connect. Keep this key
 		// safe as you can only download it once.
-		privateKey = ioutil.ReadFile("path/to/key")
+		privateKey = os.ReadFile("path/to/key")
 
 		auth, err = asc.NewTokenConfig(keyID, issuerID, expiryDuration, privateKey)
 		if err != nil {
diff --git a/asc/provisioning_certificates.go b/asc/provisioning_certificates.go
index fc6378c..8787fe0 100644
--- a/asc/provisioning_certificates.go
+++ b/asc/provisioning_certificates.go
@@ -25,7 +25,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 )
 
 // ErrMissingCSRContent happens when CreateCertificate is provided a nil Reader for processing
@@ -144,7 +143,7 @@ func (s *ProvisioningService) CreateCertificate(ctx context.Context, certificate
 		return nil, nil, ErrMissingCSRContent
 	}
 
-	csrBytes, err := ioutil.ReadAll(csrContent)
+	csrBytes, err := io.ReadAll(csrContent)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/asc/upload_operation_test.go b/asc/upload_operation_test.go
index 4ea8935..5c95900 100644
--- a/asc/upload_operation_test.go
+++ b/asc/upload_operation_test.go
@@ -26,7 +26,6 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"testing"
@@ -35,7 +34,7 @@ import (
 )
 
 func TestMultipartUpload(t *testing.T) {
-	file, err := ioutil.TempFile("", "big_file")
+	file, err := os.CreateTemp("", "big_file")
 	if err != nil {
 		assert.FailNow(t, "temp file creation produced an error", err)
 	}
@@ -112,7 +111,7 @@ func TestMultipartUpload(t *testing.T) {
 }
 
 func TestUploadOperationChunk(t *testing.T) {
-	file, err := ioutil.TempFile("", "small_file")
+	file, err := os.CreateTemp("", "small_file")
 	if err != nil {
 		assert.FailNow(t, "temp file creation produced an error", err)
 	}
@@ -153,7 +152,7 @@ func TestUploadOperationChunk(t *testing.T) {
 }
 
 func TestUploadOperationUploadError_InvalidOperation(t *testing.T) {
-	file, err := ioutil.TempFile("", "big_file")
+	file, err := os.CreateTemp("", "big_file")
 	if err != nil {
 		assert.FailNow(t, "temp file creation produced an error", err)
 	}
@@ -190,8 +189,7 @@ func TestUploadOperationUploadError_InvalidOperation(t *testing.T) {
 
 // rmFile closes an open descriptor.
 func rmFile(f *os.File) {
-	err := os.Remove(f.Name())
-	if err != nil {
+	if err := os.Remove(f.Name()); err != nil {
 		fmt.Println(err)
 	}
 }
diff --git a/examples/util/util.go b/examples/util/util.go
index 90909c5..ffdd45c 100644
--- a/examples/util/util.go
+++ b/examples/util/util.go
@@ -26,8 +26,8 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
+	"os"
 	"time"
 
 	"github.com/cidertool/asc-go/asc"
@@ -47,7 +47,7 @@ func TokenConfig() (auth *asc.AuthTransport, err error) {
 		secret = []byte(*privateKey)
 	} else if *privateKeyPath != "" {
 		// Read private key file as []byte
-		secret, err = ioutil.ReadFile(*privateKeyPath)
+		secret, err = os.ReadFile(*privateKeyPath)
 		if err != nil {
 			return nil, err
 		}
diff --git a/go.mod b/go.mod
index 1cacf6e..99d17c6 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/cidertool/asc-go
 
-go 1.13
+go 1.16
 
 require (
 	github.com/cenkalti/backoff/v4 v4.1.0
diff --git a/test/integration/asc_test.go b/test/integration/asc_test.go
index 5d20377..c160074 100644
--- a/test/integration/asc_test.go
+++ b/test/integration/asc_test.go
@@ -24,7 +24,6 @@ package integration
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"time"
 
@@ -58,7 +57,7 @@ func tokenConfig() *asc.AuthTransport {
 		privateKey = []byte(key)
 	} else if keyPath := os.Getenv(envPrivateKeyPath); keyPath != "" {
 		// Read private key file as []byte
-		privateKey, err = ioutil.ReadFile(keyPath)
+		privateKey, err = os.ReadFile(keyPath)
 		if err != nil {
 			fmt.Println(err)
 			return nil