diff --git a/files_map.go b/files_map.go
new file mode 100644
index 0000000..90eb232
--- /dev/null
+++ b/files_map.go
@@ -0,0 +1,99 @@
+// Code generated by github.com/gobuffalo/mapgen. DO NOT EDIT.
+
+package pkger
+
+import (
+	"sort"
+	"sync"
+)
+
+// filesMap wraps sync.Map and uses the following types:
+// key:   Path
+// value: *File
+type filesMap struct {
+	data *sync.Map
+	init sync.Once
+}
+
+func (m *filesMap) Data() *sync.Map {
+	m.init.Do(func() {
+		if m.data == nil {
+			m.data = &sync.Map{}
+		}
+	})
+	return m.data
+}
+
+// Delete the key from the map
+func (m *filesMap) Delete(key Path) {
+	m.Data().Delete(key)
+}
+
+// Load the key from the map.
+// Returns *File or bool.
+// A false return indicates either the key was not found
+// or the value is not of type *File
+func (m *filesMap) Load(key Path) (*File, bool) {
+	i, ok := m.Data().Load(key)
+	if !ok {
+		return nil, false
+	}
+	s, ok := i.(*File)
+	return s, ok
+}
+
+// LoadOrStore will return an existing key or
+// store the value if not already in the map
+func (m *filesMap) LoadOrStore(key Path, value *File) (*File, bool) {
+	i, _ := m.Data().LoadOrStore(key, value)
+	s, ok := i.(*File)
+	return s, ok
+}
+
+// LoadOr will return an existing key or
+// run the function and store the results
+func (m *filesMap) LoadOr(key Path, fn func(*filesMap) (*File, bool)) (*File, bool) {
+	i, ok := m.Load(key)
+	if ok {
+		return i, ok
+	}
+	i, ok = fn(m)
+	if ok {
+		m.Store(key, i)
+		return i, ok
+	}
+	return i, false
+}
+
+// Range over the *File values in the map
+func (m *filesMap) Range(f func(key Path, value *File) bool) {
+	m.Data().Range(func(k, v interface{}) bool {
+		key, ok := k.(Path)
+		if !ok {
+			return false
+		}
+		value, ok := v.(*File)
+		if !ok {
+			return false
+		}
+		return f(key, value)
+	})
+}
+
+// Store a *File in the map
+func (m *filesMap) Store(key Path, value *File) {
+	m.Data().Store(key, value)
+}
+
+// Keys returns a list of keys in the map
+func (m *filesMap) Keys() []Path {
+	var keys []Path
+	m.Range(func(key Path, value *File) bool {
+		keys = append(keys, key)
+		return true
+	})
+	sort.Slice(keys, func(a, b int) bool {
+		return keys[a].String() <= keys[b].String()
+	})
+	return keys
+}
diff --git a/index.go b/index.go
index 95ceab4..acdb95d 100644
--- a/index.go
+++ b/index.go
@@ -13,7 +13,7 @@ import (
 )
 
 type index struct {
-	Files   map[Path]*File
+	Files   *filesMap
 	Infos   map[string]here.Info
 	current here.Info
 	once    sync.Once
@@ -61,7 +61,7 @@ func (i *index) Create(pt Path) (*File, error) {
 		},
 	}
 
-	i.Files[pt] = f
+	i.Files.Store(pt, f)
 	return f, nil
 }
 
@@ -70,12 +70,17 @@ func (i *index) MarshalJSON() ([]byte, error) {
 
 	fm := map[string]json.RawMessage{}
 
-	for k, v := range i.Files {
-		b, err := v.MarshalJSON()
+	var err error
+	i.Files.Range(func(key Path, value *File) bool {
+		b, err := value.MarshalJSON()
 		if err != nil {
-			return b, err
+			return false
 		}
-		fm[k.String()] = b
+		fm[key.String()] = b
+		return true
+	})
+	if err != nil {
+		return nil, err
 	}
 
 	m["files"] = fm
@@ -91,19 +96,22 @@ func (i *index) UnmarshalJSON(b []byte) error {
 }
 
 func (i index) Walk(pt Path, wf WalkFunc) error {
-	if len(i.Files) > 0 {
-		for k, v := range i.Files {
-			if k.Pkg != pt.Pkg {
-				continue
-			}
-			if err := wf(k, v.info); err != nil {
-				return err
-			}
+	var err error
+	i.Files.Range(func(k Path, v *File) bool {
+		if k.Pkg != pt.Pkg {
+			return true
 		}
+		if err = wf(k, v.info); err != nil {
+			return false
+		}
+		return true
+	})
+
+	if err != nil {
+		return err
 	}
 
 	var info here.Info
-	var err error
 	if pt.Pkg == "." {
 		info, err = Current()
 		if err != nil {
@@ -136,7 +144,7 @@ func (i index) Walk(pt Path, wf WalkFunc) error {
 }
 
 func (i *index) Open(pt Path) (*File, error) {
-	f, ok := i.Files[pt]
+	f, ok := i.Files.Load(pt)
 	if !ok {
 		return i.openDisk(pt)
 	}
@@ -174,7 +182,7 @@ func (i index) openDisk(pt Path) (*File, error) {
 
 func newIndex() *index {
 	return &index{
-		Files: map[Path]*File{},
+		Files: &filesMap{},
 		Infos: map[string]here.Info{},
 	}
 }
diff --git a/parser/parser_test.go b/parser/parser_test.go
index fd525cb..874413d 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -14,7 +14,7 @@ func Test_Parser(t *testing.T) {
 
 	r.NoError(err)
 
-	exp := []string{"github.com/gobuffalo/buffalo:/logo.svg", "github.com/markbates/pkger:/internal/app/public", "github.com/markbates/pkger:/internal/app/templates/a.txt", "github.com/markbates/pkger:internal/app/public/images/mark-small.png", "github.com/markbates/pkger:internal/app/public/images/mark.png", "github.com/markbates/pkger:internal/app/public/images/mark_250px.png", "github.com/markbates/pkger:internal/app/public/images/mark_400px.png", "github.com/markbates/pkger:internal/app/public/index.html"}
+	exp := []string{"github.com/gobuffalo/buffalo:/logo.svg", "github.com/markbates/pkger:/internal/app/public", "github.com/markbates/pkger:/internal/app/templates/a.txt", "github.com/markbates/pkger:/internal/app/public/images/mark-small.png", "github.com/markbates/pkger:/internal/app/public/images/mark.png", "github.com/markbates/pkger:/internal/app/public/images/mark_250px.png", "github.com/markbates/pkger:/internal/app/public/images/mark_400px.png", "github.com/markbates/pkger:/internal/app/public/index.html"}
 	sort.Strings(exp)
 
 	act := make([]string, len(res.Paths))
diff --git a/pkger.go b/pkger.go
index 2ccd174..9141459 100644
--- a/pkger.go
+++ b/pkger.go
@@ -62,7 +62,7 @@ func Pack(out io.Writer, paths []Path) error {
 		if fi.IsDir() {
 			continue
 		}
-		rootIndex.Files[p] = f
+		rootIndex.Files.Store(p, f)
 		f.Close()
 	}
 	return json.NewEncoder(out).Encode(rootIndex)