diff --git a/config/main.go b/config/main.go
index ea55a18..54e1592 100644
--- a/config/main.go
+++ b/config/main.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"sort"
@@ -63,12 +64,12 @@ func start() error {
 	}
 
 	err = registerAsDatabase()
-	if err != nil && !os.IsNotExist(err) {
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
 		return err
 	}
 
 	err = loadConfig(false)
-	if err != nil && !os.IsNotExist(err) {
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
 		return err
 	}
 	return nil
diff --git a/database/registry.go b/database/registry.go
index 2694c14..44dcbae 100644
--- a/database/registry.go
+++ b/database/registry.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"path"
 	"regexp"
@@ -116,7 +117,7 @@ func loadRegistry() error {
 	filePath := path.Join(rootStructure.Path, registryFileName)
 	data, err := os.ReadFile(filePath)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			return nil
 		}
 		return err
diff --git a/database/storage/fstree/fstree.go b/database/storage/fstree/fstree.go
index dfc9e17..2ef0277 100644
--- a/database/storage/fstree/fstree.go
+++ b/database/storage/fstree/fstree.go
@@ -8,6 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -46,7 +47,7 @@ func NewFSTree(name, location string) (storage.Interface, error) {
 
 	file, err := os.Stat(basePath)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			err = os.MkdirAll(basePath, defaultDirMode)
 			if err != nil {
 				return nil, fmt.Errorf("fstree: failed to create directory %s: %w", basePath, err)
@@ -89,7 +90,7 @@ func (fst *FSTree) Get(key string) (record.Record, error) {
 
 	data, err := os.ReadFile(dstPath)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			return nil, storage.ErrNotFound
 		}
 		return nil, fmt.Errorf("fstree: failed to read file %s: %w", dstPath, err)
@@ -176,7 +177,7 @@ func (fst *FSTree) Query(q *query.Query, local, internal bool) (*iterator.Iterat
 		walkRoot = walkPrefix
 	case err == nil:
 		walkRoot = filepath.Dir(walkPrefix)
-	case os.IsNotExist(err):
+	case errors.Is(err, fs.ErrNotExist):
 		walkRoot = filepath.Dir(walkPrefix)
 	default: // err != nil
 		return nil, fmt.Errorf("fstree: could not stat query root %s: %w", walkPrefix, err)
@@ -211,7 +212,7 @@ func (fst *FSTree) queryExecutor(walkRoot string, queryIter *iterator.Iterator,
 		// read file
 		data, err := os.ReadFile(path)
 		if err != nil {
-			if os.IsNotExist(err) {
+			if errors.Is(err, fs.ErrNotExist) {
 				return nil
 			}
 			return fmt.Errorf("fstree: failed to read file %s: %w", path, err)
@@ -274,7 +275,7 @@ func (fst *FSTree) Shutdown() error {
 	return nil
 }
 
-// writeFile mirrors ioutil.WriteFile, replacing an existing file with the same
+// writeFile mirrors os.WriteFile, replacing an existing file with the same
 // name atomically. This is not atomic on Windows, but still an improvement.
 // TODO: Replace with github.com/google/renamio.WriteFile as soon as it is fixed on Windows.
 // TODO: This has become a wont-fix. Explore other options.
diff --git a/updater/file.go b/updater/file.go
index 2eb1957..f408ced 100644
--- a/updater/file.go
+++ b/updater/file.go
@@ -1,7 +1,9 @@
 package updater
 
 import (
+	"errors"
 	"io"
+	"io/fs"
 	"os"
 	"strings"
 
@@ -121,7 +123,7 @@ func (file *File) Unpack(suffix string, unpacker Unpacker) (string, error) {
 		return path, nil
 	}
 
-	if !os.IsNotExist(err) {
+	if !errors.Is(err, fs.ErrNotExist) {
 		return "", err
 	}
 
diff --git a/updater/resource.go b/updater/resource.go
index ca177b3..8aaa75c 100644
--- a/updater/resource.go
+++ b/updater/resource.go
@@ -489,7 +489,7 @@ boundarySearch:
 
 		// Remove if it exists, or an error occurs on access.
 		_, err = os.Stat(unpackedPath)
-		if err == nil || !os.IsNotExist(err) {
+		if err == nil || !errors.Is(err, fs.ErrNotExist) {
 			err = os.Remove(unpackedPath)
 			if err != nil {
 				log.Warningf("%s: failed to purge unpacked resource %s v%s: %s", res.registry.Name, rv.resource.Identifier, rv.VersionNumber, err)
diff --git a/updater/unpacking.go b/updater/unpacking.go
index e602dc6..ac6e786 100644
--- a/updater/unpacking.go
+++ b/updater/unpacking.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"path"
 	"path/filepath"
@@ -88,7 +89,7 @@ func (res *Resource) unpackZipArchive() error {
 	// Check status of destination.
 	dstStat, err := os.Stat(destDir)
 	switch {
-	case os.IsNotExist(err):
+	case errors.Is(err, fs.ErrNotExist):
 		// The destination does not exist, continue with unpacking.
 	case err != nil:
 		return fmt.Errorf("cannot access destination for unpacking: %w", err)
diff --git a/utils/atomic.go b/utils/atomic.go
index cde4a1a..6e1b87f 100644
--- a/utils/atomic.go
+++ b/utils/atomic.go
@@ -1,8 +1,10 @@
 package utils
 
 import (
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 
 	"github.com/safing/portbase/utils/renameio"
@@ -94,7 +96,7 @@ func ReplaceFileAtomic(dest string, src string, opts *AtomicFileOptions) error {
 		stat, err := os.Stat(dest)
 		if err == nil {
 			opts.Mode = stat.Mode()
-		} else if !os.IsNotExist(err) {
+		} else if !errors.Is(err, fs.ErrNotExist) {
 			return err
 		}
 	}
diff --git a/utils/fs.go b/utils/fs.go
index 87d2d59..b612a06 100644
--- a/utils/fs.go
+++ b/utils/fs.go
@@ -33,7 +33,7 @@ func EnsureDirectory(path string, perm os.FileMode) error {
 		}
 	}
 	// file does not exist (or has been deleted)
-	if err == nil || os.IsNotExist(err) {
+	if err == nil || errors.Is(err, fs.ErrNotExist) {
 		err = os.Mkdir(path, perm)
 		if err != nil {
 			return fmt.Errorf("could not create dir %s: %w", path, err)
diff --git a/utils/renameio/tempfile.go b/utils/renameio/tempfile.go
index 270bbc9..9397789 100644
--- a/utils/renameio/tempfile.go
+++ b/utils/renameio/tempfile.go
@@ -1,6 +1,8 @@
 package renameio
 
 import (
+	"errors"
+	"io/fs"
 	"os"
 	"path/filepath"
 )
@@ -137,7 +139,7 @@ func TempFile(dir, path string) (*PendingFile, error) {
 func Symlink(oldname, newname string) error {
 	// Fast path: if newname does not exist yet, we can skip the whole dance
 	// below.
-	if err := os.Symlink(oldname, newname); err == nil || !os.IsExist(err) {
+	if err := os.Symlink(oldname, newname); err == nil || !errors.Is(err, fs.ErrExist) {
 		return err
 	}
 
diff --git a/utils/renameio/writefile.go b/utils/renameio/writefile.go
index 4f3dc03..2115302 100644
--- a/utils/renameio/writefile.go
+++ b/utils/renameio/writefile.go
@@ -2,7 +2,7 @@ package renameio
 
 import "os"
 
-// WriteFile mirrors ioutil.WriteFile, replacing an existing file with the same
+// WriteFile mirrors os.WriteFile, replacing an existing file with the same
 // name atomically.
 func WriteFile(filename string, data []byte, perm os.FileMode) error {
 	t, err := TempFile("", filename)