diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 7dc1486..d52919c 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -4,34 +4,34 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.16.x]
+        go-version: [1.x]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
-    - name: Install Go
-      uses: actions/setup-go@v1
-      with:
-        go-version: ${{ matrix.go-version }}
-    - name: Install staticcheck
-      run: go install honnef.co/go/tools/cmd/staticcheck@latest
-      shell: bash
-    - name: Install golint
-      run: go install golang.org/x/lint/golint@latest
-      shell: bash
-    - name: Update PATH
-      run: echo "$(go env GOPATH)/bin" >> $GITHUB_PATH
-      shell: bash
-    - name: Checkout code
-      uses: actions/checkout@v1
-    - name: Fmt
-      if: matrix.platform != 'windows-latest' # :(
-      run: "diff <(gofmt -d .) <(printf '')"
-      shell: bash
-    - name: Vet
-      run: go vet ./...
-    - name: Staticcheck
-      run: staticcheck ./...
-    - name: Lint
-      run: golint ./...
-    - name: Test
-      run: go test -race ./...
+      - name: Install Go
+        uses: actions/setup-go@v1
+        with:
+          go-version: ${{ matrix.go-version }}
+      - name: Install staticcheck
+        run: go install honnef.co/go/tools/cmd/staticcheck@latest
+        shell: bash
+      - name: Install golint
+        run: go install golang.org/x/lint/golint@latest
+        shell: bash
+      - name: Update PATH
+        run: echo "$(go env GOPATH)/bin" >> $GITHUB_PATH
+        shell: bash
+      - name: Checkout code
+        uses: actions/checkout@v1
+      - name: Fmt
+        if: matrix.platform != 'windows-latest' # :(
+        run: "diff <(gofmt -d .) <(printf '')"
+        shell: bash
+      - name: Vet
+        run: go vet ./...
+      - name: Staticcheck
+        run: staticcheck ./...
+      - name: Lint
+        run: golint ./...
+      - name: Test
+        run: go test -race ./...
diff --git a/ffcli/command_test.go b/ffcli/command_test.go
index 45b1100..7656a85 100644
--- a/ffcli/command_test.go
+++ b/ffcli/command_test.go
@@ -6,7 +6,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"reflect"
 	"strings"
@@ -326,10 +326,10 @@ func TestIssue57(t *testing.T) {
 
 	for _, testcase := range []struct {
 		args        []string
-		parseErrAs  error
+		parseErrAs  any
 		parseErrIs  error
 		parseErrStr string
-		runErrAs    error
+		runErrAs    any
 		runErrIs    error
 		runErrStr   string
 	}{
@@ -374,7 +374,7 @@ func TestIssue57(t *testing.T) {
 	} {
 		t.Run(strings.Join(append([]string{"foo"}, testcase.args...), " "), func(t *testing.T) {
 			fs := flag.NewFlagSet("·", flag.ContinueOnError)
-			fs.SetOutput(ioutil.Discard)
+			fs.SetOutput(io.Discard)
 
 			var (
 				baz = &ffcli.Command{Name: "baz", FlagSet: fs, Exec: func(_ context.Context, args []string) error { return nil }}
diff --git a/fftest/tempfile.go b/fftest/tempfile.go
index f7bfdf5..cfb5c0f 100644
--- a/fftest/tempfile.go
+++ b/fftest/tempfile.go
@@ -1,34 +1,26 @@
 package fftest
 
 import (
-	"io/ioutil"
+	"math/rand"
 	"os"
+	"path/filepath"
+	"strconv"
 	"testing"
 )
 
-// TempFile uses ioutil.TempFile to create a temporary file with the given
-// content. Use the cleanup func to remove the file.
-func TempFile(t *testing.T, content string) (filename string, cleanup func()) {
+// TempFile returns the filename of a temporary file that has been created with
+// the provided content. The file is created in t.TempDir(), which is
+// automatically removed when the test finishes.
+func TempFile(t *testing.T, content string) string {
 	t.Helper()
 
-	f, err := ioutil.TempFile("", "fftest_")
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if _, err := f.Write([]byte(content)); err != nil {
-		t.Fatal(err)
-	}
+	filename := filepath.Join(t.TempDir(), strconv.Itoa(rand.Int()))
 
-	if err := f.Close(); err != nil {
+	if err := os.WriteFile(filename, []byte(content), 0600); err != nil {
 		t.Fatal(err)
 	}
 
-	cleanup = func() {
-		if err := os.Remove(f.Name()); err != nil {
-			t.Errorf("os.Remove(%q): %v", f.Name(), err)
-		}
-	}
+	t.Logf("created %s", filename)
 
-	return f.Name(), cleanup
+	return filename
 }
diff --git a/fftoml/fftoml.go b/fftoml/fftoml.go
index d57451d..03e628e 100644
--- a/fftoml/fftoml.go
+++ b/fftoml/fftoml.go
@@ -54,8 +54,8 @@ type Option func(*ConfigFileParser)
 //
 // For example, given the following TOML
 //
-//     [section.subsection]
-//     value = 10
+//	[section.subsection]
+//	value = 10
 //
 // Parse will match to a flag with the name `-section.subsection.value` by default.
 // If the delimiter is "-", Parse will match to `-section-subsection-value` instead.
diff --git a/go.mod b/go.mod
index 09de5a6..e0dfa50 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/peterbourgon/ff/v3
 
-go 1.16
+go 1.18
 
 require (
 	github.com/pelletier/go-toml v1.9.5
diff --git a/parse_test.go b/parse_test.go
index 8404699..9717f7b 100644
--- a/parse_test.go
+++ b/parse_test.go
@@ -204,8 +204,7 @@ func TestParseIssue16(t *testing.T) {
 		},
 	} {
 		t.Run(testcase.name, func(t *testing.T) {
-			filename, cleanup := fftest.TempFile(t, testcase.data)
-			defer cleanup()
+			filename := fftest.TempFile(t, testcase.data)
 
 			fs, vars := fftest.Pair()
 			vars.ParseError = ff.Parse(fs, []string{},
@@ -245,9 +244,7 @@ func TestParseConfigFile(t *testing.T) {
 		t.Run(testcase.name, func(t *testing.T) {
 			filename := "dummy"
 			if !testcase.missing {
-				var cleanup func()
-				filename, cleanup = fftest.TempFile(t, "")
-				defer cleanup()
+				filename = fftest.TempFile(t, "")
 			}
 
 			options := []ff.Option{ff.WithConfigFile(filename), ff.WithConfigFileParser(ff.PlainParser)}