diff --git a/backend/posix/posix.go b/backend/posix/posix.go
index b5bd9a7..828b4a6 100644
--- a/backend/posix/posix.go
+++ b/backend/posix/posix.go
@@ -6,7 +6,6 @@ import (
 	"encoding/hex"
 	"fmt"
 	"io"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"sort"
@@ -964,20 +963,21 @@ func (p *Posix) ListObjects(bucket, prefix, marker, delim string, maxkeys int) (
 		return nil, fmt.Errorf("stat bucket: %w", err)
 	}
 
-	results, err := walk(bucket, prefix, delim, marker, maxkeys)
+	fileSystem := os.DirFS(bucket)
+	results, err := backend.Walk(fileSystem, prefix, delim, marker, maxkeys)
 	if err != nil {
 		return nil, fmt.Errorf("walk %v: %w", bucket, err)
 	}
 
 	return &s3.ListObjectsOutput{
-		CommonPrefixes: results.commonPrefixes,
-		Contents:       results.objects,
+		CommonPrefixes: results.CommonPrefixes,
+		Contents:       results.Objects,
 		Delimiter:      &delim,
-		IsTruncated:    results.truncated,
+		IsTruncated:    results.Truncated,
 		Marker:         &marker,
 		MaxKeys:        int32(maxkeys),
 		Name:           &bucket,
-		NextMarker:     &results.nextMarker,
+		NextMarker:     &results.NextMarker,
 		Prefix:         &prefix,
 	}, nil
 }
@@ -990,177 +990,21 @@ func (p *Posix) ListObjectsV2(bucket, prefix, marker, delim string, maxkeys int)
 		return nil, fmt.Errorf("stat bucket: %w", err)
 	}
 
-	results, err := walk(bucket, prefix, delim, marker, maxkeys)
+	fileSystem := os.DirFS(bucket)
+	results, err := backend.Walk(fileSystem, prefix, delim, marker, maxkeys)
 	if err != nil {
 		return nil, fmt.Errorf("walk %v: %w", bucket, err)
 	}
 
 	return &s3.ListObjectsV2Output{
-		CommonPrefixes:        results.commonPrefixes,
-		Contents:              results.objects,
+		CommonPrefixes:        results.CommonPrefixes,
+		Contents:              results.Objects,
 		Delimiter:             &delim,
-		IsTruncated:           results.truncated,
+		IsTruncated:           results.Truncated,
 		ContinuationToken:     &marker,
 		MaxKeys:               int32(maxkeys),
 		Name:                  &bucket,
-		NextContinuationToken: &results.nextMarker,
+		NextContinuationToken: &results.NextMarker,
 		Prefix:                &prefix,
 	}, nil
 }
-
-type walkResults struct {
-	commonPrefixes []types.CommonPrefix
-	objects        []types.Object
-	truncated      bool
-	nextMarker     string
-}
-
-func walk(root, prefix, delimiter, marker string, max int) (walkResults, error) {
-	fileSystem := os.DirFS(root)
-	cpmap := make(map[string]struct{})
-	var objects []types.Object
-
-	var pastMarker bool
-	if marker == "" {
-		pastMarker = true
-	}
-
-	var pastMax bool
-	var newMarker string
-	var truncated bool
-
-	err := fs.WalkDir(fileSystem, ".", func(path string, d fs.DirEntry, err error) error {
-		if err != nil {
-			return err
-		}
-
-		if pastMax {
-			newMarker = path
-			truncated = true
-			return fs.SkipAll
-		}
-
-		if d.IsDir() {
-			// Ignore the root directory
-			if path == "." {
-				return nil
-			}
-
-			// If prefix is defined and the directory does not match prefix,
-			// do not descend into the directory because nothing will
-			// match this prefix.  Make sure to append the / at the end of
-			// directories since this is implied as a directory path name.
-			if prefix != "" && !strings.HasPrefix(path+string(os.PathSeparator), prefix) {
-				return fs.SkipDir
-			}
-
-			// TODO: special case handling if directory is empty
-			// and was "PUT" explicitly
-			return nil
-		}
-
-		if !pastMarker {
-			if path != marker {
-				return nil
-			}
-			pastMarker = true
-		}
-
-		// If object doesnt have prefix, dont include in results.
-		if prefix != "" && !strings.HasPrefix(path, prefix) {
-			return nil
-		}
-
-		if delimiter == "" {
-			// If no delimeter specified, then all files with matching
-			// prefix are included in results
-			fi, err := d.Info()
-			if err != nil {
-				return fmt.Errorf("get info for %v: %w", path, err)
-			}
-
-			objects = append(objects, types.Object{
-				ETag:         new(string),
-				Key:          &path,
-				LastModified: backend.GetTimePtr(fi.ModTime()),
-				Size:         fi.Size(),
-			})
-			if (len(objects) + len(cpmap)) == max {
-				pastMax = true
-			}
-			return nil
-		}
-
-		// Since delimiter is specified, we only want results that
-		// do not contain the delimiter beyond the prefix.  If the
-		// delimiter exists past the prefix, then the substring
-		// between the prefix and delimiter is part of common prefixes.
-		//
-		// For example:
-		// prefix = A/
-		// delimeter = /
-		// and objects:
-		// A/file
-		// A/B/file
-		// B/C
-		// would return:
-		// objects: A/file
-		// common prefix: A/B/
-		//
-		// Note: No obects are included past the common prefix since
-		// these are all rolled up into the common prefix.
-		// Note: The delimeter can be anything, so we have to operate on
-		// the full path without any assumptions on posix directory heirarchy
-		// here.  Usually the delimeter with be "/", but thats not required.
-		suffix := strings.TrimPrefix(path, prefix)
-		before, _, found := strings.Cut(suffix, delimiter)
-		if !found {
-			fi, err := d.Info()
-			if err != nil {
-				return fmt.Errorf("get info for %v: %w", path, err)
-			}
-			objects = append(objects, types.Object{
-				ETag:         new(string),
-				Key:          &path,
-				LastModified: backend.GetTimePtr(fi.ModTime()),
-				Size:         fi.Size(),
-			})
-			if (len(objects) + len(cpmap)) == max {
-				pastMax = true
-			}
-			return nil
-		}
-
-		// Common prefixes are a set, so should not have duplicates.
-		// These are abstractly a "directory", so need to include the
-		// delimeter at the end.
-		cpmap[prefix+before+delimiter] = struct{}{}
-		if (len(objects) + len(cpmap)) == max {
-			pastMax = true
-		}
-
-		return nil
-	})
-	if err != nil {
-		return walkResults{}, err
-	}
-
-	commonPrefixStrings := make([]string, 0, len(cpmap))
-	for k := range cpmap {
-		commonPrefixStrings = append(commonPrefixStrings, k)
-	}
-	sort.Strings(commonPrefixStrings)
-	commonPrefixes := make([]types.CommonPrefix, 0, len(commonPrefixStrings))
-	for _, cp := range commonPrefixStrings {
-		commonPrefixes = append(commonPrefixes, types.CommonPrefix{
-			Prefix: &cp,
-		})
-	}
-
-	return walkResults{
-		commonPrefixes: commonPrefixes,
-		objects:        objects,
-		truncated:      truncated,
-		nextMarker:     newMarker,
-	}, nil
-}
diff --git a/backend/walk.go b/backend/walk.go
new file mode 100644
index 0000000..de78033
--- /dev/null
+++ b/backend/walk.go
@@ -0,0 +1,169 @@
+package backend
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"sort"
+	"strings"
+
+	"github.com/aws/aws-sdk-go-v2/service/s3/types"
+)
+
+type WalkResults struct {
+	CommonPrefixes []types.CommonPrefix
+	Objects        []types.Object
+	Truncated      bool
+	NextMarker     string
+}
+
+// Walk walks the supplied fs.FS and returns results compatible with list
+// objects responses
+func Walk(fileSystem fs.FS, prefix, delimiter, marker string, max int) (WalkResults, error) {
+	cpmap := make(map[string]struct{})
+	var objects []types.Object
+
+	var pastMarker bool
+	if marker == "" {
+		pastMarker = true
+	}
+
+	var pastMax bool
+	var newMarker string
+	var truncated bool
+
+	err := fs.WalkDir(fileSystem, ".", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if pastMax {
+			newMarker = path
+			truncated = true
+			return fs.SkipAll
+		}
+
+		if d.IsDir() {
+			// Ignore the root directory
+			if path == "." {
+				return nil
+			}
+
+			// If prefix is defined and the directory does not match prefix,
+			// do not descend into the directory because nothing will
+			// match this prefix.  Make sure to append the / at the end of
+			// directories since this is implied as a directory path name.
+			if prefix != "" && !strings.HasPrefix(path+string(os.PathSeparator), prefix) {
+				return fs.SkipDir
+			}
+
+			// TODO: special case handling if directory is empty
+			// and was "PUT" explicitly
+			return nil
+		}
+
+		if !pastMarker {
+			if path != marker {
+				return nil
+			}
+			pastMarker = true
+		}
+
+		// If object doesnt have prefix, dont include in results.
+		if prefix != "" && !strings.HasPrefix(path, prefix) {
+			return nil
+		}
+
+		if delimiter == "" {
+			// If no delimeter specified, then all files with matching
+			// prefix are included in results
+			fi, err := d.Info()
+			if err != nil {
+				return fmt.Errorf("get info for %v: %w", path, err)
+			}
+
+			objects = append(objects, types.Object{
+				ETag:         new(string),
+				Key:          &path,
+				LastModified: GetTimePtr(fi.ModTime()),
+				Size:         fi.Size(),
+			})
+			if (len(objects) + len(cpmap)) == max {
+				pastMax = true
+			}
+			return nil
+		}
+
+		// Since delimiter is specified, we only want results that
+		// do not contain the delimiter beyond the prefix.  If the
+		// delimiter exists past the prefix, then the substring
+		// between the prefix and delimiter is part of common prefixes.
+		//
+		// For example:
+		// prefix = A/
+		// delimeter = /
+		// and objects:
+		// A/file
+		// A/B/file
+		// B/C
+		// would return:
+		// objects: A/file
+		// common prefix: A/B/
+		//
+		// Note: No obects are included past the common prefix since
+		// these are all rolled up into the common prefix.
+		// Note: The delimeter can be anything, so we have to operate on
+		// the full path without any assumptions on posix directory heirarchy
+		// here.  Usually the delimeter with be "/", but thats not required.
+		suffix := strings.TrimPrefix(path, prefix)
+		before, _, found := strings.Cut(suffix, delimiter)
+		if !found {
+			fi, err := d.Info()
+			if err != nil {
+				return fmt.Errorf("get info for %v: %w", path, err)
+			}
+			objects = append(objects, types.Object{
+				ETag:         new(string),
+				Key:          &path,
+				LastModified: GetTimePtr(fi.ModTime()),
+				Size:         fi.Size(),
+			})
+			if (len(objects) + len(cpmap)) == max {
+				pastMax = true
+			}
+			return nil
+		}
+
+		// Common prefixes are a set, so should not have duplicates.
+		// These are abstractly a "directory", so need to include the
+		// delimeter at the end.
+		cpmap[prefix+before+delimiter] = struct{}{}
+		if (len(objects) + len(cpmap)) == max {
+			pastMax = true
+		}
+
+		return nil
+	})
+	if err != nil {
+		return WalkResults{}, err
+	}
+
+	commonPrefixStrings := make([]string, 0, len(cpmap))
+	for k := range cpmap {
+		commonPrefixStrings = append(commonPrefixStrings, k)
+	}
+	sort.Strings(commonPrefixStrings)
+	commonPrefixes := make([]types.CommonPrefix, 0, len(commonPrefixStrings))
+	for _, cp := range commonPrefixStrings {
+		commonPrefixes = append(commonPrefixes, types.CommonPrefix{
+			Prefix: &cp,
+		})
+	}
+
+	return WalkResults{
+		CommonPrefixes: commonPrefixes,
+		Objects:        objects,
+		Truncated:      truncated,
+		NextMarker:     newMarker,
+	}, nil
+}
diff --git a/backend/walk_test.go b/backend/walk_test.go
new file mode 100644
index 0000000..075b73c
--- /dev/null
+++ b/backend/walk_test.go
@@ -0,0 +1,128 @@
+package backend_test
+
+import (
+	"io/fs"
+	"testing"
+	"testing/fstest"
+
+	"github.com/aws/aws-sdk-go-v2/service/s3/types"
+	"github.com/versity/scoutgw/backend"
+)
+
+type walkTest struct {
+	fsys     fs.FS
+	expected backend.WalkResults
+}
+
+func TestWalk(t *testing.T) {
+	tests := []walkTest{{
+		// test case from
+		// https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-prefixes.html
+		fsys: fstest.MapFS{
+			"sample.jpg":                       {},
+			"photos/2006/January/sample.jpg":   {},
+			"photos/2006/February/sample2.jpg": {},
+			"photos/2006/February/sample3.jpg": {},
+			"photos/2006/February/sample4.jpg": {},
+		},
+		expected: backend.WalkResults{
+			CommonPrefixes: []types.CommonPrefix{{
+				Prefix: backend.GetStringPtr("photos/"),
+			}},
+			Objects: []types.Object{{
+				Key: backend.GetStringPtr("sample.jpg"),
+			}},
+		},
+	}}
+
+	for _, tt := range tests {
+		res, err := backend.Walk(tt.fsys, "", "/", "", 1000)
+		if err != nil {
+			t.Fatalf("walk: %v", err)
+		}
+
+		compareResults(res, tt.expected, t)
+	}
+}
+
+func compareResults(got, wanted backend.WalkResults, t *testing.T) {
+	if !compareCommonPrefix(got.CommonPrefixes, wanted.CommonPrefixes) {
+		t.Errorf("unexpected common prefix, got %v wanted %v",
+			printCommonPrefixes(got.CommonPrefixes),
+			printCommonPrefixes(wanted.CommonPrefixes))
+	}
+
+	if !compareObjects(got.Objects, wanted.Objects) {
+		t.Errorf("unexpected common prefix, got %v wanted %v",
+			printObjects(got.Objects),
+			printObjects(wanted.Objects))
+	}
+}
+
+func compareCommonPrefix(a, b []types.CommonPrefix) bool {
+	if len(a) != len(b) {
+		return false
+	}
+
+	for _, cp := range a {
+		if containsCommonPrefix(cp, b) {
+			return true
+		}
+	}
+	return false
+}
+
+func containsCommonPrefix(c types.CommonPrefix, list []types.CommonPrefix) bool {
+	for _, cp := range list {
+		if *c.Prefix == *cp.Prefix {
+			return true
+		}
+	}
+	return false
+}
+
+func printCommonPrefixes(list []types.CommonPrefix) string {
+	res := "["
+	for _, cp := range list {
+		if res == "[" {
+			res = res + *cp.Prefix
+		} else {
+			res = res + ", " + *cp.Prefix
+		}
+	}
+	return res + "]"
+}
+
+func compareObjects(a, b []types.Object) bool {
+	if len(a) != len(b) {
+		return false
+	}
+
+	for _, cp := range a {
+		if containsObject(cp, b) {
+			return true
+		}
+	}
+	return false
+}
+
+func containsObject(c types.Object, list []types.Object) bool {
+	for _, cp := range list {
+		if *c.Key == *cp.Key {
+			return true
+		}
+	}
+	return false
+}
+
+func printObjects(list []types.Object) string {
+	res := "["
+	for _, cp := range list {
+		if res == "[" {
+			res = res + *cp.Key
+		} else {
+			res = res + ", " + *cp.Key
+		}
+	}
+	return res + "]"
+}