diff --git a/core/net/src/main/java/org/onosproject/net/host/impl/HostMonitor.java b/core/net/src/main/java/org/onosproject/net/host/impl/HostMonitor.java
index 4dc93a5..5fb1dcf 100644
--- a/core/net/src/main/java/org/onosproject/net/host/impl/HostMonitor.java
+++ b/core/net/src/main/java/org/onosproject/net/host/impl/HostMonitor.java
@@ -168,7 +168,9 @@
             }
         }
 
-        this.timeout = Timer.getTimer().newTimeout(this, probeRate, TimeUnit.MILLISECONDS);
+        synchronized (this) {
+            this.timeout = Timer.getTimer().newTimeout(this, probeRate, TimeUnit.MILLISECONDS);
+        }
     }
 
     /**