diff --git a/core/api/src/main/java/org/onlab/onos/net/topology/Topology.java b/core/api/src/main/java/org/onlab/onos/net/topology/Topology.java
index f71a5ec..ea3c68d 100644
--- a/core/api/src/main/java/org/onlab/onos/net/topology/Topology.java
+++ b/core/api/src/main/java/org/onlab/onos/net/topology/Topology.java
@@ -7,6 +7,8 @@
  */
 public interface Topology extends Provided {
 
+    // FIXME: Following is not true right now. It is actually System.nanoTime(),
+    // which has no relation to epoch time, wall clock, etc.
     /**
      * Returns the time, specified in milliseconds since start of epoch,
      * when the topology became active and made available.