diff --git a/qm.adoc b/qm.adoc
index c2912c2..b43b5c0 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -581,12 +581,15 @@ include::qm.conf.5-opts.adoc[]
 Locks
 -----
 
-Online migrations and backups (`vzdump`) set a lock to prevent incompatible
-concurrent actions on the affected VMs. Sometimes you need to remove such a
-lock manually (e.g., after a power failure).
+Online migrations, snapshots and backups (`vzdump`) set a lock to
+prevent incompatible concurrent actions on the affected VMs. Sometimes
+you need to remove such a lock manually (e.g., after a power failure).
 
  qm unlock <vmid>
 
+CAUTION: Only do that if you are sure the action which set the lock is
+no longer running.
+
 
 ifdef::manvolnum[]