diff --git a/copyOnWriteFs_test.go b/copyOnWriteFs_test.go
new file mode 100644
index 0000000..2a00fab
--- /dev/null
+++ b/copyOnWriteFs_test.go
@@ -0,0 +1,23 @@
+package afero
+
+import "testing"
+
+func TestCopyOnWrite(t *testing.T) {
+	var fs Fs
+	var err error
+	base := NewOsFs()
+	roBase := NewReadOnlyFs(base)
+	ufs := NewCopyOnWriteFs(roBase, NewMemMapFs())
+	fs = ufs
+	err = fs.MkdirAll("nonexistent/directory/", 0744)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	_, err = fs.Create("nonexistent/directory/newfile")
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+}