diff --git a/src/cluster.c b/src/cluster.c
index fe8675f2..327cbecc 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -1279,22 +1279,33 @@ void clusterCron(void) {
     di = dictGetIterator(server.cluster->nodes);
     while((de = dictNext(di)) != NULL) {
         clusterNode *node = dictGetVal(de);
+        time_t now = time(NULL);
         int delay;
 
         if (node->flags &
             (REDIS_NODE_MYSELF|REDIS_NODE_NOADDR|REDIS_NODE_HANDSHAKE))
                 continue;
+
         /* Check only if we already sent a ping and did not received
          * a reply yet. */
         if (node->ping_sent == 0 ||
             node->ping_sent <= node->pong_received) continue;
 
+        /* If our ping is older than half the cluster timeout (may happen
+         * in a cluster with many nodes), send a new ping. */
+        if (node->link &&
+            (now - node->ping_sent) > server.cluster->node_timeout/2)
+        {
+            clusterSendPing(node->link, CLUSTERMSG_TYPE_PING);
+            continue;
+        }
+
         /* If we never received a pong, use the ping time to compute
          * the delay. */
         if (node->pong_received) {
-            delay = time(NULL) - node->pong_received;
+            delay = now - node->pong_received;
         } else {
-            delay = time(NULL) - node->ping_sent;
+            delay = now - node->ping_sent;
         }
 
         if (delay < server.cluster->node_timeout) {