diff --git a/basepath.go b/basepath.go
index 6ec6ca9..5e4fc2e 100644
--- a/basepath.go
+++ b/basepath.go
@@ -52,7 +52,7 @@
 	// On Windows a common mistake would be to provide an absolute OS path
 	// We could strip out the base part, but that would not be very portable.
 	if filepath.IsAbs(name) {
-		return &os.PathError{"realPath", name, errors.New("got a real OS path instead of a virtual")}
+		return &os.PathError{Op: "realPath", Path: name, Err: errors.New("got a real OS path instead of a virtual")}
 	}
 
 	return nil
@@ -60,14 +60,14 @@
 
 func (b *BasePathFs) Chtimes(name string, atime, mtime time.Time) (err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return &os.PathError{"chtimes", name, err}
+		return &os.PathError{Op: "chtimes", Path: name, Err: err}
 	}
 	return b.source.Chtimes(name, atime, mtime)
 }
 
 func (b *BasePathFs) Chmod(name string, mode os.FileMode) (err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return &os.PathError{"chmod", name, err}
+		return &os.PathError{Op: "chmod", Path: name, Err: err}
 	}
 	return b.source.Chmod(name, mode)
 }
@@ -78,66 +78,66 @@
 
 func (b *BasePathFs) Stat(name string) (fi os.FileInfo, err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return nil, &os.PathError{"stat", name, err}
+		return nil, &os.PathError{Op: "stat", Path: name, Err: err}
 	}
 	return b.source.Stat(name)
 }
 
 func (b *BasePathFs) Rename(oldname, newname string) (err error) {
 	if oldname, err = b.RealPath(oldname); err != nil {
-		return &os.PathError{"rename", oldname, err}
+		return &os.PathError{Op: "rename", Path: oldname, Err: err}
 	}
 	if newname, err = b.RealPath(newname); err != nil {
-		return &os.PathError{"rename", newname, err}
+		return &os.PathError{Op: "rename", Path: newname, Err: err}
 	}
 	return b.source.Rename(oldname, newname)
 }
 
 func (b *BasePathFs) RemoveAll(name string) (err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return &os.PathError{"remove_all", name, err}
+		return &os.PathError{Op: "remove_all", Path: name, Err: err}
 	}
 	return b.source.RemoveAll(name)
 }
 
 func (b *BasePathFs) Remove(name string) (err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return &os.PathError{"remove", name, err}
+		return &os.PathError{Op: "remove", Path: name, Err: err}
 	}
 	return b.source.Remove(name)
 }
 
 func (b *BasePathFs) OpenFile(name string, flag int, mode os.FileMode) (f File, err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return nil, &os.PathError{"openfile", name, err}
+		return nil, &os.PathError{Op: "openfile", Path: name, Err: err}
 	}
 	return b.source.OpenFile(name, flag, mode)
 }
 
 func (b *BasePathFs) Open(name string) (f File, err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return nil, &os.PathError{"open", name, err}
+		return nil, &os.PathError{Op: "open", Path: name, Err: err}
 	}
 	return b.source.Open(name)
 }
 
 func (b *BasePathFs) Mkdir(name string, mode os.FileMode) (err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return &os.PathError{"mkdir", name, err}
+		return &os.PathError{Op: "mkdir", Path: name, Err: err}
 	}
 	return b.source.Mkdir(name, mode)
 }
 
 func (b *BasePathFs) MkdirAll(name string, mode os.FileMode) (err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return &os.PathError{"mkdir", name, err}
+		return &os.PathError{Op: "mkdir", Path: name, Err: err}
 	}
 	return b.source.MkdirAll(name, mode)
 }
 
 func (b *BasePathFs) Create(name string) (f File, err error) {
 	if name, err = b.RealPath(name); err != nil {
-		return nil, &os.PathError{"create", name, err}
+		return nil, &os.PathError{Op: "create", Path: name, Err: err}
 	}
 	return b.source.Create(name)
 }
diff --git a/composite_test.go b/composite_test.go
index a8af48f..e8ac1a8 100644
--- a/composite_test.go
+++ b/composite_test.go
@@ -187,7 +187,7 @@
 	fh, _ = ufs.Open("/home/test/foo")
 	list, err := fh.Readdir(-1)
 	if err != nil {
-		t.Errorf("Readdir failed", err)
+		t.Errorf("Readdir failed %s", err)
 	}
 	if len(list) != 2 {
 		for _, x := range list {
@@ -220,7 +220,7 @@
 	fh, _ = ufs.Open("/home/test/foo")
 	list, err := fh.Readdir(-1)
 	if err != nil {
-		t.Errorf("Readdir failed", err)
+		t.Errorf("Readdir failed %s", err)
 	}
 	if len(list) != 2 {
 		for _, x := range list {
@@ -255,7 +255,7 @@
 	list, err := fh.Readdir(-1)
 	fh.Close()
 	if err != nil {
-		t.Errorf("Readdir failed", err)
+		t.Errorf("Readdir failed %s", err)
 	}
 	if len(list) != 2 {
 		for _, x := range list {
diff --git a/mem/file.go b/mem/file.go
index 3c1e09a..e41e012 100644
--- a/mem/file.go
+++ b/mem/file.go
@@ -186,7 +186,7 @@
 		return ErrFileClosed
 	}
 	if f.readOnly {
-		return &os.PathError{"truncate", f.fileData.name, errors.New("file handle is read only")}
+		return &os.PathError{Op: "truncate", Path: f.fileData.name, Err: errors.New("file handle is read only")}
 	}
 	if size < 0 {
 		return ErrOutOfRange
@@ -218,7 +218,7 @@
 
 func (f *File) Write(b []byte) (n int, err error) {
 	if f.readOnly {
-		return 0, &os.PathError{"write", f.fileData.name, errors.New("file handle is read only")}
+		return 0, &os.PathError{Op: "write", Path: f.fileData.name, Err: errors.New("file handle is read only")}
 	}
 	n = len(b)
 	cur := atomic.LoadInt64(&f.at)
diff --git a/memmap.go b/memmap.go
index 494ba54..767ac1d 100644
--- a/memmap.go
+++ b/memmap.go
@@ -45,7 +45,7 @@
 	return m.data
 }
 
-func (MemMapFs) Name() string { return "MemMapFS" }
+func (*MemMapFs) Name() string { return "MemMapFS" }
 
 func (m *MemMapFs) Create(name string) (File, error) {
 	name = normalizePath(name)
@@ -108,7 +108,7 @@
 	x, ok := m.getData()[name]
 	if ok {
 		// Only return ErrFileExists if it's a file, not a directory.
-		i := mem.FileInfo{x}
+		i := mem.FileInfo{FileData: x}
 		if !i.IsDir() {
 			return ErrFileExists
 		}
@@ -127,7 +127,7 @@
 	_, ok := m.getData()[name]
 	m.mu.RUnlock()
 	if ok {
-		return &os.PathError{"mkdir", name, ErrFileExists}
+		return &os.PathError{Op: "mkdir", Path: name, Err: ErrFileExists}
 	}
 
 	m.mu.Lock()
@@ -190,7 +190,7 @@
 	f, ok := m.getData()[name]
 	m.mu.RUnlock()
 	if !ok {
-		return nil, &os.PathError{"open", name, ErrFileNotFound}
+		return nil, &os.PathError{Op: "open", Path: name, Err: ErrFileNotFound}
 	}
 	return f, nil
 }
@@ -247,11 +247,11 @@
 	if _, ok := m.getData()[name]; ok {
 		err := m.unRegisterWithParent(name)
 		if err != nil {
-			return &os.PathError{"remove", name, err}
+			return &os.PathError{Op: "remove", Path: name, Err: err}
 		}
 		delete(m.getData(), name)
 	} else {
-		return &os.PathError{"remove", name, os.ErrNotExist}
+		return &os.PathError{Op: "remove", Path: name, Err: os.ErrNotExist}
 	}
 	return nil
 }
@@ -299,7 +299,7 @@
 		m.mu.Unlock()
 		m.mu.RLock()
 	} else {
-		return &os.PathError{"rename", oldname, ErrFileNotFound}
+		return &os.PathError{Op: "rename", Path: oldname, Err: ErrFileNotFound}
 	}
 	return nil
 }
@@ -320,7 +320,7 @@
 	f, ok := m.getData()[name]
 	m.mu.RUnlock()
 	if !ok {
-		return &os.PathError{"chmod", name, ErrFileNotFound}
+		return &os.PathError{Op: "chmod", Path: name, Err: ErrFileNotFound}
 	}
 
 	m.mu.Lock()
@@ -337,7 +337,7 @@
 	f, ok := m.getData()[name]
 	m.mu.RUnlock()
 	if !ok {
-		return &os.PathError{"chtimes", name, ErrFileNotFound}
+		return &os.PathError{Op: "chtimes", Path: name, Err: ErrFileNotFound}
 	}
 
 	m.mu.Lock()
@@ -349,7 +349,7 @@
 
 func (m *MemMapFs) List() {
 	for _, x := range m.data {
-		y := mem.FileInfo{x}
+		y := mem.FileInfo{FileData: x}
 		fmt.Println(x.Name(), y.Size())
 	}
 }
diff --git a/memmap_test.go b/memmap_test.go
index 0bd10c9..ca5abbc 100644
--- a/memmap_test.go
+++ b/memmap_test.go
@@ -105,8 +105,8 @@
 // Ensure Permissions are set on OpenFile/Mkdir/MkdirAll
 func TestPermSet(t *testing.T) {
 	const fileName = "/myFileTest"
-	const dirPath =  "/myDirTest"
-	const dirPathAll =  "/my/path/to/dir"
+	const dirPath = "/myDirTest"
+	const dirPathAll = "/my/path/to/dir"
 
 	const fileMode = os.FileMode(0765)