diff --git a/src/main/java/net/onrc/onos/api/flowmanager/FlowId.java b/src/main/java/net/onrc/onos/api/flowmanager/FlowId.java
index 9d1f0ed..f6d7f8a 100644
--- a/src/main/java/net/onrc/onos/api/flowmanager/FlowId.java
+++ b/src/main/java/net/onrc/onos/api/flowmanager/FlowId.java
@@ -1,37 +1,41 @@
 package net.onrc.onos.api.flowmanager;
 
+import java.util.Objects;
+
 import net.onrc.onos.api.batchoperation.BatchOperationTarget;
 
 /**
  * Represents ID for Flow objects.
  */
 public class FlowId implements BatchOperationTarget {
-    private final String value;
+    private final long value;
 
     /**
      * Creates new instance with string ID.
+     * <p>
+     * This FlowId instance should be generated with {@link FlowIdGenerator}.
      *
      * @param id String representation of the ID.
      */
-    public FlowId(String id) {
+    public FlowId(long id) {
         value = id;
     }
 
     @Override
     public String toString() {
-        return value;
+        return Long.toString(value);
     }
 
     @Override
     public int hashCode() {
-        return value.hashCode();
+        return Objects.hashCode(value);
     }
 
     @Override
     public boolean equals(Object obj) {
         if (obj instanceof FlowId) {
-            FlowId other = (FlowId) obj;
-            return (this.value.equals(other.value));
+            FlowId that = (FlowId) obj;
+            return Objects.equals(this.value, that.value);
         }
         return false;
     }