diff --git a/cluster2/src/main/java/io/scalecube/cluster2/AbstractAgent.java b/cluster2/src/main/java/io/scalecube/cluster2/AbstractAgent.java
index e0e21333..31486071 100644
--- a/cluster2/src/main/java/io/scalecube/cluster2/AbstractAgent.java
+++ b/cluster2/src/main/java/io/scalecube/cluster2/AbstractAgent.java
@@ -46,7 +46,7 @@ public int doWork() {
     workCount += pollMessage();
     workCount += receiveMessage();
     workCount += processTick();
-    workCount += callbackInvoker.doWork();
+    workCount += callbackInvoker != null ? callbackInvoker.doWork() : 0;
 
     return workCount;
   }
diff --git a/cluster2/src/main/java/io/scalecube/cluster2/fdetector/FailureDetector.java b/cluster2/src/main/java/io/scalecube/cluster2/fdetector/FailureDetector.java
index 132521d5..358476fc 100644
--- a/cluster2/src/main/java/io/scalecube/cluster2/fdetector/FailureDetector.java
+++ b/cluster2/src/main/java/io/scalecube/cluster2/fdetector/FailureDetector.java
@@ -289,9 +289,12 @@ Member nextPingMember() {
         return null;
       }
 
-      final int i = index == size ? index = 0 : index++;
-      if (i == 0) {
+      final int i;
+      if (index >= size) {
+        i = index = 0;
         shuffle();
+      } else {
+        i = index++;
       }
 
       return pingMembers.get(i);
diff --git a/cluster2/src/main/java/io/scalecube/cluster2/gossip/GossipProtocol.java b/cluster2/src/main/java/io/scalecube/cluster2/gossip/GossipProtocol.java
index ed57f7b3..58cc2603 100644
--- a/cluster2/src/main/java/io/scalecube/cluster2/gossip/GossipProtocol.java
+++ b/cluster2/src/main/java/io/scalecube/cluster2/gossip/GossipProtocol.java
@@ -294,13 +294,26 @@ void nextGossipMembers() {
         return;
       }
 
-      //      for (int i = 0, limit = Math.min(gossipFanout, size); i < limit; ) {
-      //        final Member member = remoteMembers.get(random.nextInt(remoteMembers.size()));
-      //        if (!gossipMembers.contains(member)) {
-      //          gossipMembers.add(member);
-      //          i++;
-      //        }
-      //      }
+      if (size <= gossipFanout) {
+        shuffle();
+        for (int i = 0; i < size; i++) {
+          gossipMembers.add(remoteMembers.get(i));
+        }
+        return;
+      }
+
+      final int step = gossipFanout;
+      final int limit = step * (size / step);
+      final int nextLimit = index + step;
+
+      if (nextLimit >= limit) {
+        index = 0;
+        shuffle();
+      }
+
+      for (; index < nextLimit; index++) {
+        gossipMembers.add(remoteMembers.get(index));
+      }
     }
 
     void shuffle() {