Setup mutator with pointer to RandomEngine instead of seed.
diff --git a/src/random.h b/src/random.h
new file mode 100644
index 0000000..d4463d3
--- /dev/null
+++ b/src/random.h
@@ -0,0 +1,26 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// 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.
+
+#ifndef SRC_RANDOM_H_
+#define SRC_RANDOM_H_
+
+#include <random>
+
+namespace protobuf_mutator {
+
+using RandomEngine = std::mt19937;
+
+} // namespace protobuf_mutator
+
+#endif // SRC_RANDOM_H_