diff --git a/src/cluster_legacy.c b/src/cluster_legacy.c
index ef5822016..678bd3d82 100644
--- a/src/cluster_legacy.c
+++ b/src/cluster_legacy.c
@@ -2,8 +2,13 @@
  * Copyright (c) 2009-Present, Redis Ltd.
  * All rights reserved.
  *
+ * Copyright (c) 2024-present, Valkey contributors.
+ * All rights reserved.
+ *
  * Licensed under your choice of the Redis Source Available License 2.0
  * (RSALv2) or the Server Side Public License v1 (SSPLv1).
+ *
+ * Portions of this file are available under BSD3 terms; see REDISCONTRIBUTIONS for more information.
  */
 
 /*
@@ -2579,9 +2584,6 @@ uint32_t writePingExt(clusterMsg *hdr, int gossipcount)  {
     extensions++;
 
     if (hdr != NULL) {
-        if (extensions != 0) {
-            hdr->mflags[0] |= CLUSTERMSG_FLAG0_EXT_DATA;
-        }
         hdr->extensions = htons(extensions);
     }
 
@@ -2771,6 +2773,9 @@ int clusterProcessPacket(clusterLink *link) {
     }
 
     sender = getNodeFromLinkAndMsg(link, hdr);
+    if (sender && (hdr->mflags[0] & CLUSTERMSG_FLAG0_EXT_DATA)) {
+        sender->flags |= CLUSTER_NODE_EXTENSIONS_SUPPORTED;
+    }
 
     /* Update the last time we saw any data from this node. We
      * use this in order to avoid detecting a timeout from a node that
@@ -3536,6 +3541,8 @@ static void clusterBuildMessageHdr(clusterMsg *hdr, int type, size_t msglen) {
     /* Set the message flags. */
     if (clusterNodeIsMaster(myself) && server.cluster->mf_end)
         hdr->mflags[0] |= CLUSTERMSG_FLAG0_PAUSED;
+    hdr->mflags[0] |= CLUSTERMSG_FLAG0_EXT_DATA; /* Always make other nodes know that
+                                                  * this node supports extension data. */
 
     hdr->totlen = htonl(msglen);
 }
@@ -3614,7 +3621,9 @@ void clusterSendPing(clusterLink *link, int type) {
      * to put inside the packet. */
     estlen = sizeof(clusterMsg) - sizeof(union clusterMsgData);
     estlen += (sizeof(clusterMsgDataGossip)*(wanted + pfail_wanted));
-    estlen += writePingExt(NULL, 0);
+    if (link->node && nodeSupportsExtensions(link->node)) {
+        estlen += writePingExt(NULL, 0);
+    }
     /* Note: clusterBuildMessageHdr() expects the buffer to be always at least
      * sizeof(clusterMsg) or more. */
     if (estlen < (int)sizeof(clusterMsg)) estlen = sizeof(clusterMsg);
@@ -3684,7 +3693,9 @@ void clusterSendPing(clusterLink *link, int type) {
 
     /* Compute the actual total length and send! */
     uint32_t totlen = 0;
-    totlen += writePingExt(hdr, gossipcount);
+    if (link->node && nodeSupportsExtensions(link->node)) {
+        totlen += writePingExt(hdr, gossipcount);
+    }
     totlen += sizeof(clusterMsg)-sizeof(union clusterMsgData);
     totlen += (sizeof(clusterMsgDataGossip)*gossipcount);
     serverAssert(gossipcount < USHRT_MAX);
diff --git a/src/cluster_legacy.h b/src/cluster_legacy.h
index a857184ab..c0144ad9c 100644
--- a/src/cluster_legacy.h
+++ b/src/cluster_legacy.h
@@ -1,3 +1,16 @@
+/*
+ * Copyright (c) 2009-Present, Redis Ltd.
+ * All rights reserved.
+ *
+ * Copyright (c) 2024-present, Valkey contributors.
+ * All rights reserved.
+ *
+ * Licensed under your choice of the Redis Source Available License 2.0
+ * (RSALv2) or the Server Side Public License v1 (SSPLv1).
+ *
+ * Portions of this file are available under BSD3 terms; see REDISCONTRIBUTIONS for more information.
+ */
+
 #ifndef CLUSTER_LEGACY_H
 #define CLUSTER_LEGACY_H
 
@@ -51,6 +64,7 @@ typedef struct clusterLink {
 #define CLUSTER_NODE_MEET 128     /* Send a MEET message to this node */
 #define CLUSTER_NODE_MIGRATE_TO 256 /* Master eligible for replica migration. */
 #define CLUSTER_NODE_NOFAILOVER 512 /* Slave will not try to failover. */
+#define CLUSTER_NODE_EXTENSIONS_SUPPORTED 1024 /* This node supports extensions. */
 #define CLUSTER_NODE_NULL_NAME "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"
 
 #define nodeIsSlave(n) ((n)->flags & CLUSTER_NODE_SLAVE)
@@ -59,6 +73,7 @@ typedef struct clusterLink {
 #define nodeTimedOut(n) ((n)->flags & CLUSTER_NODE_PFAIL)
 #define nodeFailed(n) ((n)->flags & CLUSTER_NODE_FAIL)
 #define nodeCantFailover(n) ((n)->flags & CLUSTER_NODE_NOFAILOVER)
+#define nodeSupportsExtensions(n) ((n)->flags & CLUSTER_NODE_EXTENSIONS_SUPPORTED)
 
 /* This structure represent elements of node->fail_reports. */
 typedef struct clusterNodeFailReport {
diff --git a/tests/unit/cluster/hostnames.tcl b/tests/unit/cluster/hostnames.tcl
index f31824062..1b4bd9dc7 100644
--- a/tests/unit/cluster/hostnames.tcl
+++ b/tests/unit/cluster/hostnames.tcl
@@ -1,3 +1,16 @@
+#
+# Copyright (c) 2009-Present, Redis Ltd.
+# All rights reserved.
+#
+# Copyright (c) 2024-present, Valkey contributors.
+# All rights reserved.
+#
+# Licensed under your choice of the Redis Source Available License 2.0
+# (RSALv2) or the Server Side Public License v1 (SSPLv1).
+#
+# Portions of this file are available under BSD3 terms; see REDISCONTRIBUTIONS for more information.
+#
+
 proc get_slot_field {slot_output shard_id node_id attrib_id} {
     return [lindex [lindex [lindex $slot_output $shard_id] $node_id] $attrib_id]
 }
@@ -116,10 +129,11 @@ test "Verify the nodes configured with prefer hostname only show hostname for ne
     # Have everyone forget node 6 and isolate it from the cluster.
     isolate_node 6
 
-    # Set hostnames for the masters, now that the node is isolated
-    R 0 config set cluster-announce-hostname "shard-1.com"
-    R 1 config set cluster-announce-hostname "shard-2.com"
-    R 2 config set cluster-announce-hostname "shard-3.com"
+    set primaries 3
+    for {set j 0} {$j < $primaries} {incr j} {
+        # Set hostnames for the masters, now that the node is isolated
+        R $j config set cluster-announce-hostname "shard-$j.com"
+    }
 
     # Prevent Node 0 and Node 6 from properly meeting,
     # they'll hang in the handshake phase. This allows us to 
@@ -149,9 +163,17 @@ test "Verify the nodes configured with prefer hostname only show hostname for ne
     } else {
         fail "Node did not learn about the 2 shards it can talk to"
     }
-    set slot_result [R 6 CLUSTER SLOTS]
-    assert_equal [lindex [get_slot_field $slot_result 0 2 3] 1] "shard-2.com"
-    assert_equal [lindex [get_slot_field $slot_result 1 2 3] 1] "shard-3.com"
+    wait_for_condition 50 100 {
+        [lindex [get_slot_field [R 6 CLUSTER SLOTS] 0 2 3] 1] eq "shard-1.com"
+    } else {
+        fail "hostname for shard-1 didn't reach node 6"
+    }
+
+    wait_for_condition 50 100 {
+        [lindex [get_slot_field [R 6 CLUSTER SLOTS] 1 2 3] 1] eq "shard-2.com"
+    } else {
+        fail "hostname for shard-2 didn't reach node 6"
+    }
 
     # Also make sure we know about the isolated master, we 
     # just can't reach it.
@@ -170,10 +192,14 @@ test "Verify the nodes configured with prefer hostname only show hostname for ne
     } else {
         fail "Node did not learn about the 2 shards it can talk to"
     }
-    set slot_result [R 6 CLUSTER SLOTS]
-    assert_equal [lindex [get_slot_field $slot_result 0 2 3] 1] "shard-1.com"
-    assert_equal [lindex [get_slot_field $slot_result 1 2 3] 1] "shard-2.com"
-    assert_equal [lindex [get_slot_field $slot_result 2 2 3] 1] "shard-3.com"
+
+    for {set j 0} {$j < $primaries} {incr j} {
+        wait_for_condition 50 100 {
+            [lindex [get_slot_field [R 6 CLUSTER SLOTS] $j 2 3] 1] eq "shard-$j.com"
+        } else {
+            fail "hostname information for shard-$j didn't reach node 6"
+        }
+    }
 }
 
 test "Test restart will keep hostname information" {