diff --git a/src/main/java/net/openhft/chronicle/map/ChronicleSet.java b/src/main/java/net/openhft/chronicle/map/ChronicleSet.java
new file mode 100644
index 000000000..aefb69e5b
--- /dev/null
+++ b/src/main/java/net/openhft/chronicle/map/ChronicleSet.java
@@ -0,0 +1,12 @@
+package net.openhft.chronicle.map;
+
+import java.util.Set;
+
+/**
+ * Created by peter on 09/10/14.
+ *
+ * TODO to be moved to Chronicle-Map
+ */
+public interface ChronicleSet<E> extends Set<E> {
+    public long longSize();
+}