diff --git a/mem/file.go b/mem/file.go
index 5a20730..5ef8b6a 100644
--- a/mem/file.go
+++ b/mem/file.go
@@ -71,7 +71,7 @@ func CreateFile(name string) *FileData {
 }
 
 func CreateDir(name string) *FileData {
-	return &FileData{name: name, memDir: &DirMap{}, dir: true}
+	return &FileData{name: name, memDir: &DirMap{}, dir: true, modtime: time.Now()}
 }
 
 func ChangeFileName(f *FileData, newname string) {
diff --git a/memmap_test.go b/memmap_test.go
index 627b106..881a61b 100644
--- a/memmap_test.go
+++ b/memmap_test.go
@@ -450,6 +450,9 @@ func TestMemFsMkdirAllMode(t *testing.T) {
 	if !info.Mode().IsDir() {
 		t.Error("/a: mode is not directory")
 	}
+	if !info.ModTime().After(time.Now().Add(-1 * time.Hour)) {
+		t.Errorf("/a: mod time not set, got %s", info.ModTime())
+	}
 	if info.Mode() != os.FileMode(os.ModeDir|0755) {
 		t.Errorf("/a: wrong permissions, expected drwxr-xr-x, got %s", info.Mode())
 	}
@@ -463,6 +466,9 @@ func TestMemFsMkdirAllMode(t *testing.T) {
 	if info.Mode() != os.FileMode(os.ModeDir|0755) {
 		t.Errorf("/a/b: wrong permissions, expected drwxr-xr-x, got %s", info.Mode())
 	}
+	if !info.ModTime().After(time.Now().Add(-1 * time.Hour)) {
+		t.Errorf("/a/b: mod time not set, got %s", info.ModTime())
+	}
 	info, err = fs.Stat("/a/b/c")
 	if err != nil {
 		t.Fatal(err)
@@ -473,6 +479,9 @@ func TestMemFsMkdirAllMode(t *testing.T) {
 	if info.Mode() != os.FileMode(os.ModeDir|0755) {
 		t.Errorf("/a/b/c: wrong permissions, expected drwxr-xr-x, got %s", info.Mode())
 	}
+	if !info.ModTime().After(time.Now().Add(-1 * time.Hour)) {
+		t.Errorf("/a/b/c: mod time not set, got %s", info.ModTime())
+	}
 }
 
 // MkdirAll does not change permissions of already-existing directories