diff --git a/pkg/operator/ceph/object/bucket/provisioner.go b/pkg/operator/ceph/object/bucket/provisioner.go
index 53ff585c3..d37d8e2d0 100644
--- a/pkg/operator/ceph/object/bucket/provisioner.go
+++ b/pkg/operator/ceph/object/bucket/provisioner.go
@@ -68,10 +68,7 @@ func (p Provisioner) GenerateUserID(obc *v1alpha1.ObjectBucketClaim, ob *v1alpha
 		return getCephUser(ob), nil
 	}
 
-	username, err := p.genUserName(obc.Name, obc.Namespace)
-	if err != nil {
-		return "", errors.Wrap(err, "failed to generate user id for OBC")
-	}
+	username := p.genUserName(obc)
 
 	return username, nil
 }
diff --git a/pkg/operator/ceph/object/bucket/rgw-handlers.go b/pkg/operator/ceph/object/bucket/rgw-handlers.go
index 435e1b9ae..193f24e48 100644
--- a/pkg/operator/ceph/object/bucket/rgw-handlers.go
+++ b/pkg/operator/ceph/object/bucket/rgw-handlers.go
@@ -2,6 +2,7 @@ package bucket
 
 import (
 	"github.com/ceph/go-ceph/rgw/admin"
+	"github.com/kube-object-storage/lib-bucket-provisioner/pkg/apis/objectbucket.io/v1alpha1"
 	"github.com/pkg/errors"
 )
 
@@ -47,15 +48,14 @@ func (p *Provisioner) createCephUser(username string) (accKey string, secKey str
 	return u.Keys[0].AccessKey, u.Keys[0].SecretKey, nil
 }
 
-func (p *Provisioner) genUserName(obcName, obcNamespace string) (string, error) {
-	// user name can be deterministically generated by obc name and namespace. since there can't be
-	// 2 obcs in the same namespace w/ the same name, this won't collide w/in the same k8s cluster.
-	// However, it can collide in multisite setups, so use the Ceph cluster FSID
-	fsid := p.clusterInfo.FSID
-	if p.clusterInfo.FSID == "" {
-		return "", errors.Errorf("failed to find ceph cluster FSID")
-	}
-	return "obc-" + obcNamespace + "-" + obcName + "-" + fsid, nil
+func (p *Provisioner) genUserName(obc *v1alpha1.ObjectBucketClaim) string {
+	// A deterministic user name can be generated from the OBC's UID. We
+	// cannot simply use the OBC's namespace and name, because they can be
+	// reused, while the preceding bucket might be retained by reclaimPolicy.
+	// But we still include namespace and name for usability. RadosGW user
+	// names have a high enough length limit, so we don't need to crop the
+	// "obc-namespace-name-" part.
+	return "obc-" + obc.Namespace + "-" + obc.Name + "-" + string(obc.UID)
 }
 
 // Delete the user and bucket created by OBC with help of radosgw-admin commands