diff --git a/filter_test.go b/filter_test.go
index dcbc6f4..679cf92 100644
--- a/filter_test.go
+++ b/filter_test.go
@@ -13,7 +13,7 @@ func TestFilterReadOnly(t *testing.T) {
 	if err == nil {
 		t.Errorf("Did not fail to create file")
 	}
-	t.Logf("ERR=%s", err)
+	// t.Logf("ERR=%s", err)
 }
 
 func TestFilterReadonlyRemoveAndRead(t *testing.T) {
@@ -59,9 +59,10 @@ func TestFilterRegexp(t *testing.T) {
 	fs.AddFilter(NewRegexpFilter(regexp.MustCompile(`\.txt$`)))
 	_, err := fs.Create("/file.html")
 	if err == nil {
+
 		t.Errorf("Did not fail to create file")
 	}
-	t.Logf("ERR=%s", err)
+	// t.Logf("ERR=%s", err)
 }
 
 func TestFilterRORegexpChain(t *testing.T) {
@@ -73,7 +74,7 @@ func TestFilterRORegexpChain(t *testing.T) {
 	if err == nil {
 		t.Errorf("Did not fail to create file")
 	}
-	t.Logf("ERR=%s", err)
+	// t.Logf("ERR=%s", err)
 }
 
 func TestFilterRegexReadDir(t *testing.T) {
diff --git a/mem/file.go b/mem/file.go
index e92d943..7d43a52 100644
--- a/mem/file.go
+++ b/mem/file.go
@@ -33,6 +33,7 @@ type File struct {
 	at           int64
 	readDirCount int64
 	closed       bool
+	readOnly     bool
 	fileData     *FileData
 }
 
@@ -40,6 +41,10 @@ func NewFileHandle(data *FileData) *File {
 	return &File{fileData: data}
 }
 
+func NewReadOnlyFileHandle(data *FileData) *File {
+	return &File{fileData: data, readOnly: true}
+}
+
 func (f File) Data() *FileData {
 	return f.fileData
 }
@@ -203,6 +208,9 @@ func (f *File) Seek(offset int64, whence int) (int64, error) {
 }
 
 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")}
+	}
 	n = len(b)
 	cur := atomic.LoadInt64(&f.at)
 	f.fileData.Lock()
diff --git a/memmap.go b/memmap.go
index 2c1ba39..2f2c612 100644
--- a/memmap.go
+++ b/memmap.go
@@ -163,6 +163,22 @@ func normalizePath(path string) string {
 }
 
 func (m *MemMapFs) Open(name string) (File, error) {
+	f, err := m.open(name)
+	if f != nil {
+		return mem.NewReadOnlyFileHandle(f), err
+	}
+	return nil, err
+}
+
+func (m *MemMapFs) openWrite(name string) (File, error) {
+	f, err := m.open(name)
+	if f != nil {
+		return mem.NewFileHandle(f), err
+	}
+	return nil, err
+}
+
+func (m *MemMapFs) open(name string) (*mem.FileData, error) {
 	name = normalizePath(name)
 
 	m.mu.RLock()
@@ -171,7 +187,7 @@ func (m *MemMapFs) Open(name string) (File, error) {
 	if !ok {
 		return nil, &os.PathError{"open", name, ErrFileNotFound}
 	}
-	return mem.NewFileHandle(f), nil
+	return f, nil
 }
 
 func (m *MemMapFs) lockfreeOpen(name string) (*mem.FileData, error) {
@@ -185,13 +201,16 @@ func (m *MemMapFs) lockfreeOpen(name string) (*mem.FileData, error) {
 }
 
 func (m *MemMapFs) OpenFile(name string, flag int, perm os.FileMode) (File, error) {
-	file, err := m.Open(name)
+	file, err := m.openWrite(name)
 	if os.IsNotExist(err) && (flag&os.O_CREATE > 0) {
 		file, err = m.Create(name)
 	}
 	if err != nil {
 		return nil, err
 	}
+	if flag == os.O_RDONLY {
+		file = mem.NewReadOnlyFileHandle(file.(*mem.File).Data())
+	}
 	if flag&os.O_APPEND > 0 {
 		_, err = file.Seek(0, os.SEEK_END)
 		if err != nil {
diff --git a/memmap_test.go b/memmap_test.go
index d8de243..c0e6825 100644
--- a/memmap_test.go
+++ b/memmap_test.go
@@ -104,7 +104,7 @@ func checkPathError(t *testing.T, err error, op string) {
 // Fails if multiple file objects use the same file.at counter in MemMapFs
 func TestMultipleOpenFiles(t *testing.T) {
 	defer removeAllTestFiles(t)
-	const fileName = "./afero-demo2.txt"
+	const fileName = "afero-demo2.txt"
 
 	var data = make([][]byte, len(Fss))
 
@@ -113,7 +113,7 @@ func TestMultipleOpenFiles(t *testing.T) {
 		path := filepath.Join(dir, fileName)
 		fh1, err := fs.Create(path)
 		if err != nil {
-			t.Error("os.Create failed: " + err.Error())
+			t.Error("fs.Create failed: " + err.Error())
 		}
 		_, err = fh1.Write([]byte("test"))
 		if err != nil {
@@ -167,3 +167,44 @@ func TestMultipleOpenFiles(t *testing.T) {
 		}
 	}
 }
+
+// Test if file.Write() fails when opened as read only
+func TestReadOnly(t *testing.T) {
+	defer removeAllTestFiles(t)
+	const fileName = "afero-demo.txt"
+
+	for _, fs := range Fss {
+		dir := testDir(fs)
+		path := filepath.Join(dir, fileName)
+
+		f, err := fs.Create(path)
+		if err != nil {
+			t.Error(fs.Name()+":", "fs.Create failed: "+err.Error())
+		}
+		_, err = f.Write([]byte("test"))
+		if err != nil {
+			t.Error(fs.Name()+":", "Write failed: "+err.Error())
+		}
+		f.Close()
+
+		f, err = fs.Open(path)
+		if err != nil {
+			t.Error("fs.Open failed: " + err.Error())
+		}
+		_, err = f.Write([]byte("data"))
+		if err == nil {
+			t.Error(fs.Name()+":", "No write error")
+		}
+		f.Close()
+
+		f, err = fs.OpenFile(path, os.O_RDONLY, 0644)
+		if err != nil {
+			t.Error("fs.Open failed: " + err.Error())
+		}
+		_, err = f.Write([]byte("data"))
+		if err == nil {
+			t.Error(fs.Name()+":", "No write error")
+		}
+		f.Close()
+	}
+}