diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index 4292e7fb8f4..3de358f9374 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -1363,6 +1363,33 @@ AlterSubscription_refresh_seq(Subscription *sub)
 	WalReceiverConn *wrconn;
 	bool		must_use_password;
 
+	/*
+	 * Disallow a concurrent REFRESH SEQUENCES while a sequence sync worker
+	 * for this subscription is still running. This avoids a race where the
+	 * publisher's sequence advances after the current worker has fetched its
+	 * value but before it marks the sequence READY. A user may then issue
+	 * another REFRESH SEQUENCES to synchronize the updated value. Since the
+	 * affected sequences are already in the INIT state, the running worker
+	 * has no indication that a new synchronization has been requested. It
+	 * would then apply the stale value it already fetched and mark the
+	 * sequence READY, causing the new synchronization request to be lost and
+	 * preventing the updated publisher values from being synchronized.
+	 */
+	LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
+	if (logicalrep_worker_find(WORKERTYPE_SEQUENCESYNC, sub->oid, InvalidOid,
+							   true))
+	{
+		LWLockRelease(LogicalRepWorkerLock);
+		ereport(ERROR,
+				errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+		/* translator: %s is an SQL ALTER command */
+				errmsg("cannot execute %s while a sequence synchronization worker is running",
+					   "ALTER SUBSCRIPTION ... REFRESH SEQUENCES"),
+				errhint("Try again after the current synchronization completes."));
+	}
+
+	LWLockRelease(LogicalRepWorkerLock);
+
 	/* Load the library providing us libpq calls. */
 	load_file("libpqwalreceiver", false);
 
diff --git a/src/test/subscription/t/036_sequences.pl b/src/test/subscription/t/036_sequences.pl
index 2a0819aaf01..8b02b24a7e9 100644
--- a/src/test/subscription/t/036_sequences.pl
+++ b/src/test/subscription/t/036_sequences.pl
@@ -232,6 +232,10 @@ $node_publisher->safe_psql(
 	CREATE SEQUENCE regress_s4 START 10 INCREMENT 2;
 ));
 
+# Wait for the missing sequence added to be synced
+$node_subscriber->poll_query_until('postgres', $synced_query)
+  or die "Timed out while waiting for subscriber to synchronize data";
+
 ##########
 # Ensure that insufficient privileges on the publisher for a sequence
 # are reported correctly as a permission issue, not as a missing sequence.