diff --git a/SystemSdk.cpp b/SystemSdk.cpp
new file mode 100644
index 0000000..d2ee123
--- /dev/null
+++ b/SystemSdk.cpp
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "SystemSdk.h"
+
+#include <algorithm>
+
+namespace android {
+namespace vintf {
+
+SystemSdk SystemSdk::removeVersions(const SystemSdk& other) const {
+    SystemSdk ret;
+    std::set_difference(versions().begin(), versions().end(), other.versions().begin(),
+                        other.versions().end(), std::inserter(ret.mVersions, ret.mVersions.end()));
+    return ret;
+}
+
+bool SystemSdk::operator==(const SystemSdk& other) const {
+    return versions() == other.versions();
+}
+
+}  // namespace vintf
+}  // namespace android