diff --git a/cgmes/cgmes-conversion/src/main/java/com/powsybl/cgmes/conversion/Conversion.java b/cgmes/cgmes-conversion/src/main/java/com/powsybl/cgmes/conversion/Conversion.java
index 628f4a8d15d..757dd5787ac 100644
--- a/cgmes/cgmes-conversion/src/main/java/com/powsybl/cgmes/conversion/Conversion.java
+++ b/cgmes/cgmes-conversion/src/main/java/com/powsybl/cgmes/conversion/Conversion.java
@@ -639,6 +639,7 @@ private void createFictitiousVoltageLevelsForLineContainer(Context context, Stri
                 .setLowVoltageLimit(vlref.getLowVoltageLimit())
                 .setHighVoltageLimit(vlref.getHighVoltageLimit())
                 .setId(fictitiousVoltageLevelId)
+                .setFictitious(true)
                 .setName(containerName)
                 .setEnsureIdUnicity(context.config().isEnsureIdAliasUnicity())
                 .add();