diff --git a/flow-decomposition/src/main/java/com/powsybl/flow_decomposition/LossesCompensator.java b/flow-decomposition/src/main/java/com/powsybl/flow_decomposition/LossesCompensator.java
index 582d343e..874541f8 100644
--- a/flow-decomposition/src/main/java/com/powsybl/flow_decomposition/LossesCompensator.java
+++ b/flow-decomposition/src/main/java/com/powsybl/flow_decomposition/LossesCompensator.java
@@ -23,6 +23,7 @@
 class LossesCompensator {
     private final double epsilon;
     private Integer networkHash;
+    public static final String LOSSES_ID_PREFIX = "LOSSES ";
 
     LossesCompensator(double epsilon) {
         this.epsilon = epsilon;
@@ -34,7 +35,7 @@ class LossesCompensator {
     }
 
     static String getLossesId(String id) {
-        return String.format("LOSSES %s", id);
+        return LOSSES_ID_PREFIX + id;
     }
 
     public void run(Network network) {
diff --git a/flow-decomposition/src/test/java/com/powsybl/flow_decomposition/FlowDecompositionObserverTest.java b/flow-decomposition/src/test/java/com/powsybl/flow_decomposition/FlowDecompositionObserverTest.java
index 50559287..2239f08e 100644
--- a/flow-decomposition/src/test/java/com/powsybl/flow_decomposition/FlowDecompositionObserverTest.java
+++ b/flow-decomposition/src/test/java/com/powsybl/flow_decomposition/FlowDecompositionObserverTest.java
@@ -344,8 +344,7 @@ void testObserverWithEnableLossesCompensation() {
         flowComputer.run(xnecProvider, network);
 
         // there are no losses in acNodalInjection
-        String lossesId = LossesCompensator.getLossesId("");
-        report.acNodalInjections.forBaseCase().forEach((inj, p) -> assertFalse(inj.startsWith(lossesId)));
+        report.acNodalInjections.forBaseCase().forEach((inj, p) -> assertFalse(inj.startsWith(LossesCompensator.LOSSES_ID_PREFIX)));
     }
 
     private void assertEventsFired(Collection<Event> firedEvents, Event... expectedEvents) {