diff --git a/src/main/java/com/powsybl/openloadflow/graph/EvenShiloachGraphDecrementalConnectivity.java b/src/main/java/com/powsybl/openloadflow/graph/EvenShiloachGraphDecrementalConnectivity.java
index 71804b44ee..782d1792a3 100644
--- a/src/main/java/com/powsybl/openloadflow/graph/EvenShiloachGraphDecrementalConnectivity.java
+++ b/src/main/java/com/powsybl/openloadflow/graph/EvenShiloachGraphDecrementalConnectivity.java
@@ -191,7 +191,7 @@ public List<Set<V>> getSmallComponents() {
             sortedComponents = true;
             connectedComponents.sort(Comparator.comparingInt(c -> -c.size()));
         }
-        return connectedComponents.subList(1, connectedComponents.size());
+        return connectedComponents.isEmpty() ? Collections.emptyList() : connectedComponents.subList(1, connectedComponents.size());
     }
 
     private interface GraphProcess {
diff --git a/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisGraphTest.java b/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisGraphTest.java
index 86e55d5588..5227e868ad 100644
--- a/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisGraphTest.java
+++ b/src/test/java/com/powsybl/openloadflow/sa/OpenSecurityAnalysisGraphTest.java
@@ -33,14 +33,10 @@
 import org.slf4j.LoggerFactory;
 
 import javax.inject.Provider;
-import java.util.ArrayList;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 import java.util.stream.Collectors;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.*;
 
 /**
  * @author Florian Dupuy <florian.dupuy at rte-france.com>
@@ -50,7 +46,6 @@ class OpenSecurityAnalysisGraphTest {
     private static final Logger LOGGER = LoggerFactory.getLogger(OpenSecurityAnalysisGraphTest.class);
 
     private Network network;
-    private List<List<LfContingency>> reference;
     private ContingenciesProvider contingenciesProvider;
     private SecurityAnalysisParameters securityAnalysisParameters;
 
@@ -69,7 +64,6 @@ void setUp() {
             new OpenLoadFlowParameters().setSlackBusSelector(new FirstSlackBusSelector()));
         securityAnalysisParameters = new SecurityAnalysisParameters().setLoadFlowParameters(lfParameters);
 
-        reference = getLoadFlowContingencies(() -> new NaiveGraphDecrementalConnectivity<>(LfBus::getNum));
         LOGGER.info("Reference established (naive connectivity calculation) on test network containing {} branches", network.getBranchCount());
     }
 
@@ -78,7 +72,7 @@ void testEvenShiloach() {
         LOGGER.info("Test Even-Shiloach on test network containing {} branches", network.getBranchCount());
         List<List<LfContingency>> lfContingencies = getLoadFlowContingencies(EvenShiloachGraphDecrementalConnectivity::new);
         printResult(lfContingencies);
-        checkResult(lfContingencies);
+        checkResult(lfContingencies, computeReference());
     }
 
     @Test
@@ -86,10 +80,36 @@ void testMst() {
         LOGGER.info("Test Minimum Spanning Tree on test network containing {} branches", network.getBranchCount());
         List<List<LfContingency>> lfContingencies = getLoadFlowContingencies(MinimumSpanningTreeGraphDecrementalConnectivity::new);
         printResult(lfContingencies);
-        checkResult(lfContingencies);
+        checkResult(lfContingencies, computeReference());
     }
 
-    private void checkResult(List<List<LfContingency>> result) {
+    private List<List<LfContingency>> computeReference() {
+        return getLoadFlowContingencies(() -> new NaiveGraphDecrementalConnectivity<>(LfBus::getNum));
+    }
+
+    @Test
+    void testNullVertices() {
+        try {
+            network.getSwitch("B3").setOpen(true);
+            contingenciesProvider = n -> Collections.singletonList(
+                new Contingency("L1", new BranchContingency("L1")));
+            List<List<LfContingency>> reference = computeReference();
+            checkResult(getLoadFlowContingencies(MinimumSpanningTreeGraphDecrementalConnectivity::new), reference);
+            checkResult(getLoadFlowContingencies(EvenShiloachGraphDecrementalConnectivity::new), reference);
+
+            contingenciesProvider = n -> Collections.singletonList(
+                new Contingency("L2", new BranchContingency("L2")));
+            network.getSwitch("B3").setOpen(false);
+            network.getSwitch("B1").setOpen(true);
+            reference = computeReference();
+            checkResult(getLoadFlowContingencies(MinimumSpanningTreeGraphDecrementalConnectivity::new), reference);
+            checkResult(getLoadFlowContingencies(EvenShiloachGraphDecrementalConnectivity::new), reference);
+        } catch (NullPointerException e) {
+            fail();
+        }
+    }
+
+    private static void checkResult(List<List<LfContingency>> result, List<List<LfContingency>> reference) {
         assertEquals(reference.size(), result.size());
         for (int iNetwork = 0; iNetwork < result.size(); iNetwork++) {
             assertEquals(reference.get(iNetwork).size(), result.get(iNetwork).size());