diff --git a/.travis.yml b/.travis.yml
index 085fbad6..04e08788 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ language: go
 dist: focal
 
 go:
-    - "1.15.x"
+    - "1.16.x"
 
 branches:
   only:
diff --git a/Dockerfile b/Dockerfile
index a89dbaa3..9f0e8f22 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 ## build Oragono
-FROM golang:1.15-alpine AS build-env
+FROM golang:1.16-alpine AS build-env
 
 RUN apk add --no-cache git make curl sed
 
diff --git a/go.mod b/go.mod
index c25ae525..251b88f3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/oragono/oragono
 
-go 1.15
+go 1.16
 
 require (
 	code.cloudfoundry.org/bytefmt v0.0.0-20200131002437-cf55d5288a48
diff --git a/irc/config.go b/irc/config.go
index 873e55ff..94c882d9 100644
--- a/irc/config.go
+++ b/irc/config.go
@@ -10,7 +10,7 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"net"
 	"os"
@@ -917,7 +917,7 @@ func (config *Config) processExtjwt() (err error) {
 
 // LoadRawConfig loads the config without doing any consistency checks or postprocessing
 func LoadRawConfig(filename string) (config *Config, err error) {
-	data, err := ioutil.ReadFile(filename)
+	data, err := os.ReadFile(filename)
 	if err != nil {
 		return nil, err
 	}
@@ -1598,7 +1598,7 @@ func (config *Config) loadMOTD() error {
 			return err
 		}
 		defer file.Close()
-		contents, err := ioutil.ReadAll(file)
+		contents, err := io.ReadAll(file)
 		if err != nil {
 			return err
 		}
diff --git a/irc/email/dkim.go b/irc/email/dkim.go
index 538ffee6..10952478 100644
--- a/irc/email/dkim.go
+++ b/irc/email/dkim.go
@@ -6,7 +6,7 @@ package email
 import (
 	"errors"
 	dkim "github.com/toorop/go-dkim"
-	"io/ioutil"
+	"os"
 )
 
 var (
@@ -25,7 +25,7 @@ func (dkim *DKIMConfig) Postprocess() (err error) {
 		if dkim.Selector == "" || dkim.KeyFile == "" {
 			return ErrMissingFields
 		}
-		dkim.keyBytes, err = ioutil.ReadFile(dkim.KeyFile)
+		dkim.keyBytes, err = os.ReadFile(dkim.KeyFile)
 		if err != nil {
 			return err
 		}
diff --git a/irc/import.go b/irc/import.go
index 95894fdc..55e855ba 100644
--- a/irc/import.go
+++ b/irc/import.go
@@ -6,8 +6,8 @@ package irc
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"log"
+	"os"
 	"strconv"
 
 	"github.com/tidwall/buntdb"
@@ -215,7 +215,7 @@ func doImportDB(config *Config, dbImport databaseImport, tx *buntdb.Tx) (err err
 }
 
 func ImportDB(config *Config, infile string) (err error) {
-	data, err := ioutil.ReadFile(infile)
+	data, err := os.ReadFile(infile)
 	if err != nil {
 		return
 	}
diff --git a/irc/jwt/extjwt.go b/irc/jwt/extjwt.go
index 803f83e5..f754e7d5 100644
--- a/irc/jwt/extjwt.go
+++ b/irc/jwt/extjwt.go
@@ -10,7 +10,7 @@ import (
 	"encoding/pem"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"time"
 
 	"github.com/dgrijalva/jwt-go"
@@ -34,7 +34,7 @@ func (t *JwtServiceConfig) Postprocess() (err error) {
 	t.secretBytes = []byte(t.Secret)
 	t.Secret = ""
 	if t.RSAPrivateKeyFile != "" {
-		keyBytes, err := ioutil.ReadFile(t.RSAPrivateKeyFile)
+		keyBytes, err := os.ReadFile(t.RSAPrivateKeyFile)
 		if err != nil {
 			return err
 		}
diff --git a/irc/languages/languages.go b/irc/languages/languages.go
index ee7f2591..7fcb257f 100644
--- a/irc/languages/languages.go
+++ b/irc/languages/languages.go
@@ -6,7 +6,7 @@ package languages
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"sort"
 	"strconv"
@@ -72,7 +72,7 @@ func NewManager(enabled bool, path string, defaultLang string) (lm *Manager, err
 }
 
 func (lm *Manager) loadData(path string) (err error) {
-	files, err := ioutil.ReadDir(path)
+	files, err := os.ReadDir(path)
 	if err != nil {
 		return
 	}
@@ -93,7 +93,7 @@ func (lm *Manager) loadData(path string) (err error) {
 
 		// load, e.g., `zh-CN.lang.yaml`
 		var data []byte
-		data, err = ioutil.ReadFile(filepath.Join(path, name))
+		data, err = os.ReadFile(filepath.Join(path, name))
 		if err != nil {
 			return
 		}
@@ -117,7 +117,7 @@ func (lm *Manager) loadData(path string) (err error) {
 		translations := make(map[string]string)
 		for _, translationSuffix := range stringsFileSuffixes {
 			stringsFilePath := filepath.Join(path, prefix+translationSuffix)
-			data, err = ioutil.ReadFile(stringsFilePath)
+			data, err = os.ReadFile(stringsFilePath)
 			if err != nil {
 				continue // skip missing paths
 			}
diff --git a/irc/listeners.go b/irc/listeners.go
index c50138f8..740a0466 100644
--- a/irc/listeners.go
+++ b/irc/listeners.go
@@ -100,7 +100,7 @@ func (nl *NetListener) serve() {
 			} else {
 				nl.server.logger.Error("internal", "invalid connection type", nl.addr)
 			}
-		} else if err == utils.ErrNetClosing {
+		} else if err == net.ErrClosed {
 			return
 		} else {
 			nl.server.logger.Error("internal", "accept error", nl.addr, err.Error())
diff --git a/irc/utils/proxy.go b/irc/utils/proxy.go
index 584e3f34..22a48264 100644
--- a/irc/utils/proxy.go
+++ b/irc/utils/proxy.go
@@ -6,7 +6,6 @@ package utils
 import (
 	"crypto/tls"
 	"encoding/binary"
-	"errors"
 	"io"
 	"net"
 	"strings"
@@ -39,8 +38,6 @@ func (p *proxyLineError) Temporary() bool {
 
 var (
 	ErrBadProxyLine error = &proxyLineError{}
-	// TODO(golang/go#4373): replace this with the stdlib ErrNetClosing
-	ErrNetClosing = errors.New("use of closed network connection")
 )
 
 // ListenerConfig is all the information about how to process
@@ -253,7 +250,7 @@ func (rl *ReloadableListener) Accept() (conn net.Conn, err error) {
 		if err == nil {
 			conn.Close()
 		}
-		err = ErrNetClosing
+		err = net.ErrClosed
 	}
 	if err != nil {
 		return nil, err