diff --git a/cow.go b/cow.go
index ebe1aed..9e729dd 100644
--- a/cow.go
+++ b/cow.go
@@ -10,7 +10,7 @@ import (
 type Cow struct {
 	eyes            string
 	tongue          string
-	typ             string
+	typ             *CowFile
 	thoughts        rune
 	thinking        bool
 	bold            bool
@@ -25,10 +25,14 @@ type Cow struct {
 // New returns pointer of Cow struct that made by options
 func New(options ...Option) (*Cow, error) {
 	cow := &Cow{
-		eyes:        "oo",
-		tongue:      "  ",
-		thoughts:    '\\',
-		typ:         "cows/default.cow",
+		eyes:     "oo",
+		tongue:   "  ",
+		thoughts: '\\',
+		typ: &CowFile{
+			Name:         "default",
+			BasePath:     "cows",
+			LocationType: InBinary,
+		},
 		ballonWidth: 40,
 	}
 	for _, o := range options {
@@ -103,13 +107,18 @@ func adjustTo2Chars(s string) string {
 	return "  "
 }
 
-func containCows(t string) bool {
-	for _, cow := range AssetNames() {
-		if t == cow {
-			return true
+func containCows(target string) (*CowFile, error) {
+	cowPaths, err := Cows()
+	if err != nil {
+		return nil, err
+	}
+	for _, cowPath := range cowPaths {
+		cowfile, ok := cowPath.Lookup(target)
+		if ok {
+			return cowfile, nil
 		}
 	}
-	return false
+	return nil, nil
 }
 
 // NotFound is indicated not found the cowfile.
@@ -126,21 +135,17 @@ func (n *NotFound) Error() string {
 // Type specify name of the cowfile
 func Type(s string) Option {
 	if s == "" {
-		s = "cows/default.cow"
-	}
-	if !strings.HasSuffix(s, ".cow") {
-		s += ".cow"
-	}
-	if !strings.HasPrefix(s, "cows/") {
-		s = "cows/" + s
+		s = "default"
 	}
 	return func(c *Cow) error {
-		if containCows(s) {
-			c.typ = s
+		cowfile, err := containCows(s)
+		if err != nil {
+			return err
+		}
+		if cowfile != nil {
+			c.typ = cowfile
 			return nil
 		}
-		s = strings.TrimPrefix(s, "cows/")
-		s = strings.TrimSuffix(s, ".cow")
 		return &NotFound{Cowfile: s}
 	}
 }
@@ -165,20 +170,30 @@ func Thoughts(thoughts rune) Option {
 
 // Random specifies something .cow from cows directory
 func Random() Option {
-	pick := pickCow()
+	pick, err := pickCow()
 	return func(c *Cow) error {
+		if err != nil {
+			return err
+		}
 		c.typ = pick
 		return nil
 	}
 }
 
-func pickCow() string {
-	cows := AssetNames()
-	n := len(cows)
-	rand.Shuffle(n, func(i, j int) {
-		cows[i], cows[j] = cows[j], cows[i]
-	})
-	return cows[rand.Intn(n)]
+func pickCow() (*CowFile, error) {
+	cowPaths, err := Cows()
+	if err != nil {
+		return nil, err
+	}
+	cowPath := cowPaths[rand.Intn(len(cowPaths))]
+
+	n := len(cowPath.CowFiles)
+	cowfile := cowPath.CowFiles[rand.Intn(n)]
+	return &CowFile{
+		Name:         cowfile,
+		BasePath:     cowPath.Name,
+		LocationType: cowPath.LocationType,
+	}, nil
 }
 
 // Bold enables bold mode
diff --git a/cowsay.go b/cowsay.go
index 91d1a23..affd05b 100644
--- a/cowsay.go
+++ b/cowsay.go
@@ -1,7 +1,10 @@
 package cowsay
 
 import (
+	"io/ioutil"
 	"math/rand"
+	"os"
+	"path/filepath"
 	"sort"
 	"strings"
 	"time"
@@ -20,21 +23,111 @@ func Say(phrase string, options ...Option) (string, error) {
 	return cow.Say(phrase)
 }
 
+// LocationType indicates the type of COWPATH.
+type LocationType int
+
+const (
+	// InBinary indicates the COWPATH in binary.
+	InBinary LocationType = iota
+
+	// InDirectory indicates the COWPATH in your directory.
+	InDirectory
+)
+
+// CowPath is information of the COWPATH.
+type CowPath struct {
+	// Name is name of the COWPATH.
+	// If you specified `COWPATH=/foo/bar`, Name is `/foo/bar`.
+	Name string
+	// CowFiles are name of the cowfile which are trimmed ".cow" suffix.
+	CowFiles []string
+	// LocationType is the type of COWPATH
+	LocationType LocationType
+}
+
+// Lookup will look for the target cowfile in the specified path.
+// If it exists, it returns the cowfile information and true value.
+func (c *CowPath) Lookup(target string) (*CowFile, bool) {
+	for _, cowfile := range c.CowFiles {
+		if cowfile == target {
+			return &CowFile{
+				Name:         cowfile,
+				BasePath:     c.Name,
+				LocationType: c.LocationType,
+			}, true
+		}
+	}
+	return nil, false
+}
+
+// CowFile is information of the cowfile.
+type CowFile struct {
+	// Name is name of the cowfile.
+	Name string
+	// BasePath is the path which the cowpath is in.
+	BasePath string
+	// LocationType is the type of COWPATH
+	LocationType LocationType
+}
+
+// ReadAll reads the cowfile content.
+// If LocationType is InBinary, the file read from binary.
+// otherwise reads from file system.
+func (c *CowFile) ReadAll() ([]byte, error) {
+	joinedPath := filepath.Join(c.BasePath, c.Name+".cow")
+	if c.LocationType == InBinary {
+		return Asset(joinedPath)
+	}
+	return ioutil.ReadFile(joinedPath)
+}
+
 // Cows to get list of cows
-func Cows() []string {
-	assets := AssetNames()
-	cows := make([]string, 0, len(assets))
-	for _, key := range assets {
-		cows = append(cows, strings.TrimSuffix(strings.TrimPrefix(key, "cows/"), ".cow"))
+func Cows() ([]*CowPath, error) {
+	cowPaths, err := cowsFromCowPath()
+	if err != nil {
+		return nil, err
 	}
+	cowPaths = append(cowPaths, &CowPath{
+		Name:         "cows",
+		CowFiles:     CowsInBinary(),
+		LocationType: InBinary,
+	})
+	return cowPaths, nil
+}
 
-	sort.Strings(cows)
-	return cows
+func cowsFromCowPath() ([]*CowPath, error) {
+	cowPaths := make([]*CowPath, 0)
+	cowPath := os.Getenv("COWPATH")
+	if cowPath == "" {
+		return cowPaths, nil
+	}
+	paths := splitPath(cowPath)
+	for _, path := range paths {
+		dirEntries, err := ioutil.ReadDir(path)
+		if err != nil {
+			return nil, err
+		}
+		path := &CowPath{
+			Name:         path,
+			CowFiles:     []string{},
+			LocationType: InDirectory,
+		}
+		for _, entry := range dirEntries {
+			name := entry.Name()
+			if strings.HasSuffix(name, ".cow") {
+				name = strings.TrimSuffix(name, ".cow")
+				path.CowFiles = append(path.CowFiles, name)
+			}
+		}
+		sort.Strings(path.CowFiles)
+		cowPaths = append(cowPaths, path)
+	}
+	return cowPaths, nil
 }
 
 // GetCow to get cow's ascii art
 func (cow *Cow) GetCow() (string, error) {
-	src, err := Asset(cow.typ)
+	src, err := cow.typ.ReadAll()
 	if err != nil {
 		return "", err
 	}
diff --git a/cowsay_test.go b/cowsay_test.go
new file mode 100644
index 0000000..800d000
--- /dev/null
+++ b/cowsay_test.go
@@ -0,0 +1,154 @@
+package cowsay
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+)
+
+func TestCows(t *testing.T) {
+	t.Run("no set COWPATH env", func(t *testing.T) {
+		cowPaths, err := Cows()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(cowPaths) != 1 {
+			t.Fatalf("want 1, but got %d", len(cowPaths))
+		}
+		cowPath := cowPaths[0]
+		if len(cowPath.CowFiles) == 0 {
+			t.Fatalf("no cowfiles")
+		}
+
+		wantCowPath := &CowPath{
+			Name:         "cows",
+			LocationType: InBinary,
+		}
+		if diff := cmp.Diff(wantCowPath, cowPath,
+			cmpopts.IgnoreFields(CowPath{}, "CowFiles"),
+		); diff != "" {
+			t.Errorf("(-want, +got)\n%s", diff)
+		}
+	})
+
+	t.Run("set COWPATH env", func(t *testing.T) {
+		cowpath := filepath.Join("testdata", "testdir")
+
+		os.Setenv("COWPATH", cowpath)
+		defer os.Unsetenv("COWPATH")
+
+		cowPaths, err := Cows()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(cowPaths) != 2 {
+			t.Fatalf("want 2, but got %d", len(cowPaths))
+		}
+
+		wants := []*CowPath{
+			{
+				Name:         "testdata/testdir",
+				LocationType: InDirectory,
+			},
+			{
+				Name:         "cows",
+				LocationType: InBinary,
+			},
+		}
+		if diff := cmp.Diff(wants, cowPaths,
+			cmpopts.IgnoreFields(CowPath{}, "CowFiles"),
+		); diff != "" {
+			t.Errorf("(-want, +got)\n%s", diff)
+		}
+
+		if len(cowPaths[0].CowFiles) != 1 {
+			t.Fatalf("unexpected cowfiles len = %d, %+v",
+				len(cowPaths[0].CowFiles), cowPaths[0].CowFiles,
+			)
+		}
+
+		if cowPaths[0].CowFiles[0] != "test" {
+			t.Fatalf("want %q but got %q", "test", cowPaths[0].CowFiles[0])
+		}
+	})
+
+	t.Run("set COWPATH env", func(t *testing.T) {
+		os.Setenv("COWPATH", "notfound")
+		defer os.Unsetenv("COWPATH")
+
+		_, err := Cows()
+		if err == nil {
+			t.Fatal("want error")
+		}
+	})
+
+}
+
+func TestCowPath_Lookup(t *testing.T) {
+	t.Run("looked for cowfile", func(t *testing.T) {
+		c := &CowPath{
+			Name:         "basepath",
+			CowFiles:     []string{"test"},
+			LocationType: InBinary,
+		}
+		got, ok := c.Lookup("test")
+		if !ok {
+			t.Errorf("want %v", ok)
+		}
+		want := &CowFile{
+			Name:         "test",
+			BasePath:     "basepath",
+			LocationType: InBinary,
+		}
+
+		if diff := cmp.Diff(want, got); diff != "" {
+			t.Errorf("(-want, +got)\n%s", diff)
+		}
+	})
+
+	t.Run("no cowfile", func(t *testing.T) {
+		c := &CowPath{
+			Name:         "basepath",
+			CowFiles:     []string{"test"},
+			LocationType: InBinary,
+		}
+		got, ok := c.Lookup("no cowfile")
+		if ok {
+			t.Errorf("want %v", !ok)
+		}
+		if got != nil {
+			t.Error("want nil")
+		}
+	})
+}
+
+func TestCowFile_ReadAll(t *testing.T) {
+	fromTestData := &CowFile{
+		Name:         "test",
+		BasePath:     filepath.Join("testdata", "testdir"),
+		LocationType: InDirectory,
+	}
+	fromTestdataContent, err := fromTestData.ReadAll()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	fromBinary := &CowFile{
+		Name:         "default",
+		BasePath:     "cows",
+		LocationType: InBinary,
+	}
+	fromBinaryContent, err := fromBinary.ReadAll()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(fromTestdataContent, fromBinaryContent) {
+		t.Fatalf("testdata\n%s\n\nbinary%s\n", string(fromTestdataContent), string(fromBinaryContent))
+	}
+
+}
diff --git a/embed.go b/embed.go
index 2b763e7..e8bf42a 100644
--- a/embed.go
+++ b/embed.go
@@ -2,7 +2,8 @@ package cowsay
 
 import (
 	"embed"
-	"path/filepath"
+	"sort"
+	"strings"
 )
 
 //go:embed cows/*
@@ -15,17 +16,25 @@ func Asset(path string) ([]byte, error) {
 	return cowsDir.ReadFile(path)
 }
 
-// AssetNames returns the names of the assets.
+// AssetNames returns the list of filename of the assets.
 func AssetNames() []string {
-	const cows = "cows"
-	entries, err := cowsDir.ReadDir(cows)
+	entries, err := cowsDir.ReadDir("cows")
 	if err != nil {
 		panic(err)
 	}
 	names := make([]string, 0, len(entries))
 	for _, entry := range entries {
-		filename := filepath.Join(cows, entry.Name())
-		names = append(names, filename)
+		name := strings.TrimSuffix(entry.Name(), ".cow")
+		names = append(names, name)
 	}
+	sort.Strings(names)
 	return names
 }
+
+var cowsInBinary = AssetNames()
+
+// CowsInBinary returns the list of cowfiles which are in binary.
+// the list is memoized.
+func CowsInBinary() []string {
+	return cowsInBinary
+}
diff --git a/internal/cli/cli.go b/internal/cli/cli.go
index c0a3877..5109ae2 100644
--- a/internal/cli/cli.go
+++ b/internal/cli/cli.go
@@ -84,7 +84,19 @@ func (c *CLI) mow(argv []string) error {
 	}
 
 	if opts.List {
-		fmt.Println(wordwrap.WrapString(strings.Join(cowsay.Cows(), " "), 80))
+		cowPaths, err := cowsay.Cows()
+		if err != nil {
+			return err
+		}
+		for _, cowPath := range cowPaths {
+			if cowPath.LocationType == cowsay.InBinary {
+				fmt.Fprintf(c.stdout, "Cow files in binary:\n")
+			} else {
+				fmt.Fprintf(c.stdout, "Cow files in %s:\n", cowPath.Name)
+			}
+			fmt.Fprintln(c.stdout, wordwrap.WrapString(strings.Join(cowPath.CowFiles, " "), 80))
+			fmt.Fprintln(c.stdout)
+		}
 		return nil
 	}
 
diff --git a/internal/cli/cli_test.go b/internal/cli/cli_test.go
index f7b0178..4c6d178 100644
--- a/internal/cli/cli_test.go
+++ b/internal/cli/cli_test.go
@@ -125,7 +125,7 @@ func TestCLI_Run(t *testing.T) {
 					if exit != 0 {
 						t.Fatalf("unexpected exit code: %d", exit)
 					}
-					testpath := filepath.Join("testdata", cli.name, tt.testfile)
+					testpath := filepath.Join("..", "..", "testdata", cli.name, tt.testfile)
 					content, err := ioutil.ReadFile(testpath)
 					if err != nil {
 						t.Fatal(err)
diff --git a/split.go b/split.go
new file mode 100644
index 0000000..532a596
--- /dev/null
+++ b/split.go
@@ -0,0 +1,10 @@
+//go:build !windows
+// +build !windows
+
+package cowsay
+
+import "strings"
+
+func splitPath(s string) []string {
+	return strings.Split(s, ":")
+}
diff --git a/split_windows.go b/split_windows.go
new file mode 100644
index 0000000..4f000e0
--- /dev/null
+++ b/split_windows.go
@@ -0,0 +1,10 @@
+//go:build windows
+// +build windows
+
+package cowsay
+
+import "strings"
+
+func splitPath(s string) []string {
+	return strings.Split(s, ";")
+}
diff --git a/internal/cli/testdata/cowsay/W_option.txt b/testdata/cowsay/W_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/W_option.txt
rename to testdata/cowsay/W_option.txt
diff --git a/internal/cli/testdata/cowsay/b_option.txt b/testdata/cowsay/b_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/b_option.txt
rename to testdata/cowsay/b_option.txt
diff --git a/internal/cli/testdata/cowsay/d_option.txt b/testdata/cowsay/d_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/d_option.txt
rename to testdata/cowsay/d_option.txt
diff --git a/internal/cli/testdata/cowsay/eyes_option.txt b/testdata/cowsay/eyes_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/eyes_option.txt
rename to testdata/cowsay/eyes_option.txt
diff --git a/internal/cli/testdata/cowsay/f_tux_option.txt b/testdata/cowsay/f_tux_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/f_tux_option.txt
rename to testdata/cowsay/f_tux_option.txt
diff --git a/internal/cli/testdata/cowsay/g_option.txt b/testdata/cowsay/g_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/g_option.txt
rename to testdata/cowsay/g_option.txt
diff --git a/internal/cli/testdata/cowsay/n_option.txt b/testdata/cowsay/n_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/n_option.txt
rename to testdata/cowsay/n_option.txt
diff --git a/internal/cli/testdata/cowsay/p_option.txt b/testdata/cowsay/p_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/p_option.txt
rename to testdata/cowsay/p_option.txt
diff --git a/internal/cli/testdata/cowsay/s_option.txt b/testdata/cowsay/s_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/s_option.txt
rename to testdata/cowsay/s_option.txt
diff --git a/internal/cli/testdata/cowsay/t_option.txt b/testdata/cowsay/t_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/t_option.txt
rename to testdata/cowsay/t_option.txt
diff --git a/internal/cli/testdata/cowsay/tongue_option.txt b/testdata/cowsay/tongue_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/tongue_option.txt
rename to testdata/cowsay/tongue_option.txt
diff --git a/internal/cli/testdata/cowsay/wired_option.txt b/testdata/cowsay/wired_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/wired_option.txt
rename to testdata/cowsay/wired_option.txt
diff --git a/internal/cli/testdata/cowsay/y_option.txt b/testdata/cowsay/y_option.txt
similarity index 100%
rename from internal/cli/testdata/cowsay/y_option.txt
rename to testdata/cowsay/y_option.txt
diff --git a/internal/cli/testdata/cowthink/W_option.txt b/testdata/cowthink/W_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/W_option.txt
rename to testdata/cowthink/W_option.txt
diff --git a/internal/cli/testdata/cowthink/b_option.txt b/testdata/cowthink/b_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/b_option.txt
rename to testdata/cowthink/b_option.txt
diff --git a/internal/cli/testdata/cowthink/d_option.txt b/testdata/cowthink/d_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/d_option.txt
rename to testdata/cowthink/d_option.txt
diff --git a/internal/cli/testdata/cowthink/eyes_option.txt b/testdata/cowthink/eyes_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/eyes_option.txt
rename to testdata/cowthink/eyes_option.txt
diff --git a/internal/cli/testdata/cowthink/f_tux_option.txt b/testdata/cowthink/f_tux_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/f_tux_option.txt
rename to testdata/cowthink/f_tux_option.txt
diff --git a/internal/cli/testdata/cowthink/g_option.txt b/testdata/cowthink/g_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/g_option.txt
rename to testdata/cowthink/g_option.txt
diff --git a/internal/cli/testdata/cowthink/n_option.txt b/testdata/cowthink/n_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/n_option.txt
rename to testdata/cowthink/n_option.txt
diff --git a/internal/cli/testdata/cowthink/p_option.txt b/testdata/cowthink/p_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/p_option.txt
rename to testdata/cowthink/p_option.txt
diff --git a/internal/cli/testdata/cowthink/s_option.txt b/testdata/cowthink/s_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/s_option.txt
rename to testdata/cowthink/s_option.txt
diff --git a/internal/cli/testdata/cowthink/t_option.txt b/testdata/cowthink/t_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/t_option.txt
rename to testdata/cowthink/t_option.txt
diff --git a/internal/cli/testdata/cowthink/tongue_option.txt b/testdata/cowthink/tongue_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/tongue_option.txt
rename to testdata/cowthink/tongue_option.txt
diff --git a/internal/cli/testdata/cowthink/wired_option.txt b/testdata/cowthink/wired_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/wired_option.txt
rename to testdata/cowthink/wired_option.txt
diff --git a/internal/cli/testdata/cowthink/y_option.txt b/testdata/cowthink/y_option.txt
similarity index 100%
rename from internal/cli/testdata/cowthink/y_option.txt
rename to testdata/cowthink/y_option.txt
diff --git a/testdata/testdir/test.cow b/testdata/testdir/test.cow
new file mode 100644
index 0000000..684b69d
--- /dev/null
+++ b/testdata/testdir/test.cow
@@ -0,0 +1,7 @@
+$the_cow = <<EOC;
+        $thoughts   ^__^
+         $thoughts  ($eyes)\\_______
+            (__)\\       )\\/\\
+             $tongue ||----w |
+                ||     ||
+EOC