diff --git a/fs/make_test_files.go b/fs/make_test_files.go
new file mode 100644
index 000000000..805d1424f
--- /dev/null
+++ b/fs/make_test_files.go
@@ -0,0 +1,146 @@
+// +build ignore
+
+// Build a directory structure with the required number of files in
+//
+// Run with go run make_test_files.go [flag] <directory>
+package main
+
+import (
+	cryptrand "crypto/rand"
+	"flag"
+	"io"
+	"log"
+	"math/rand"
+	"os"
+	"path/filepath"
+)
+
+var (
+	// Flags
+	numberOfFiles            = flag.Int("n", 1000, "Number of files to create")
+	averageFilesPerDirectory = flag.Int("files-per-directory", 10, "Average number of files per directory")
+	maxDepth                 = flag.Int("max-depth", 10, "Maximum depth of directory heirachy")
+	minFileSize              = flag.Int64("min-size", 0, "Minimum size of file to create")
+	maxFileSize              = flag.Int64("max-size", 100, "Maximum size of files to create")
+	minFileNameLength        = flag.Int("min-name-length", 4, "Minimum size of file to create")
+	maxFileNameLength        = flag.Int("max-name-length", 12, "Maximum size of files to create")
+
+	directoriesToCreate int
+	totalDirectories    int
+	fileNames           = map[string]struct{}{} // keep a note of which file name we've used already
+)
+
+// randomString create a random string for test purposes
+func randomString(n int) string {
+	const (
+		vowel     = "aeiou"
+		consonant = "bcdfghjklmnpqrstvwxyz"
+		digit     = "0123456789"
+	)
+	pattern := []string{consonant, vowel, consonant, vowel, consonant, vowel, consonant, digit}
+	out := make([]byte, n)
+	p := 0
+	for i := range out {
+		source := pattern[p]
+		p = (p + 1) % len(pattern)
+		out[i] = source[rand.Intn(len(source))]
+	}
+	return string(out)
+}
+
+// fileName creates a unique random file or directory name
+func fileName() (name string) {
+	for {
+		length := rand.Intn(*maxFileNameLength-*minFileNameLength) + *minFileNameLength
+		name = randomString(length)
+		if _, found := fileNames[name]; !found {
+			break
+		}
+	}
+	fileNames[name] = struct{}{}
+	return name
+}
+
+// dir is a directory in the directory heirachy being built up
+type dir struct {
+	name     string
+	depth    int
+	children []*dir
+	parent   *dir
+}
+
+// Create a random directory heirachy under d
+func (d *dir) createDirectories() {
+	for totalDirectories < directoriesToCreate {
+		newDir := &dir{
+			name:   fileName(),
+			depth:  d.depth + 1,
+			parent: d,
+		}
+		d.children = append(d.children, newDir)
+		totalDirectories++
+		switch rand.Intn(4) {
+		case 0:
+			if d.depth < *maxDepth {
+				newDir.createDirectories()
+			}
+		case 1:
+			return
+		}
+	}
+	return
+}
+
+// list the directory heirachy
+func (d *dir) list(path string, output []string) []string {
+	dirPath := path + "/" + d.name
+	output = append(output, dirPath)
+	for _, subDir := range d.children {
+		output = subDir.list(dirPath, output)
+	}
+	return output
+}
+
+// writeFile writes a random file at dir/name
+func writeFile(dir, name string) {
+	err := os.MkdirAll(dir, 0777)
+	if err != nil {
+		log.Fatalf("Failed to make directory %q: %v", dir, err)
+	}
+	path := filepath.Join(dir, name)
+	fd, err := os.Create(path)
+	if err != nil {
+		log.Fatalf("Failed to open file %q: %v", path, err)
+	}
+	size := rand.Int63n(*maxFileSize-*minFileSize) + *minFileSize
+	_, err = io.CopyN(fd, cryptrand.Reader, size)
+	if err != nil {
+		log.Fatalf("Failed to write %v bytes to file %q: %v", size, path, err)
+	}
+	err = fd.Close()
+	if err != nil {
+		log.Fatalf("Failed to close file %q: %v", path, err)
+	}
+}
+
+func main() {
+	flag.Parse()
+	args := flag.Args()
+	if len(args) != 1 {
+		log.Fatalf("Require 1 directory argument")
+	}
+	outputDirectory := args[0]
+	log.Printf("Output dir %q", outputDirectory)
+
+	directoriesToCreate = *numberOfFiles / *averageFilesPerDirectory
+	log.Printf("directoriesToCreate %v", directoriesToCreate)
+	root := &dir{name: outputDirectory, depth: 1}
+	for totalDirectories < directoriesToCreate {
+		root.createDirectories()
+	}
+	dirs := root.list("", []string{})
+	for i := 0; i < *numberOfFiles; i++ {
+		dir := dirs[rand.Intn(len(dirs))]
+		writeFile(dir, fileName())
+	}
+}