diff --git a/maven-resolver-api/src/main/java/org/eclipse/aether/RepositorySystem.java b/maven-resolver-api/src/main/java/org/eclipse/aether/RepositorySystem.java
index c71c08b2a..ddad8726d 100644
--- a/maven-resolver-api/src/main/java/org/eclipse/aether/RepositorySystem.java
+++ b/maven-resolver-api/src/main/java/org/eclipse/aether/RepositorySystem.java
@@ -29,6 +29,7 @@
 import org.eclipse.aether.deployment.DeployRequest;
 import org.eclipse.aether.deployment.DeployResult;
 import org.eclipse.aether.deployment.DeploymentException;
+import org.eclipse.aether.graph.DependencyFilter;
 import org.eclipse.aether.graph.DependencyNode;
 import org.eclipse.aether.installation.InstallRequest;
 import org.eclipse.aether.installation.InstallResult;
@@ -153,10 +154,12 @@ DependencyResult resolveDependencies(RepositorySystemSession session, Dependency
      *
      * @param session The repository session, must not be {@code null}.
      * @param root The dependency node root of the graph, must not be {@code null}.
+     * @param filter The filter to apply, may be {@code null}.
      * @return The flattened list of dependency nodes, never {@code null}.
      * @since 2.0.0
      */
-    List<DependencyNode> flattenDependencyNodes(RepositorySystemSession session, DependencyNode root);
+    List<DependencyNode> flattenDependencyNodes(
+            RepositorySystemSession session, DependencyNode root, DependencyFilter filter);
 
     /**
      * Resolves the path for an artifact. The artifact will be downloaded to the local repository if necessary. An
diff --git a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultRepositorySystem.java b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultRepositorySystem.java
index 20f98dc22..d9a3254a6 100644
--- a/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultRepositorySystem.java
+++ b/maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/DefaultRepositorySystem.java
@@ -260,13 +260,8 @@ public DependencyResult resolveDependencies(RepositorySystemSession session, Dep
             throw new NullPointerException("dependency node and collect request cannot be null");
         }
 
-        final ArrayList<DependencyNode> dependencyNodes = new ArrayList<>();
-        DependencyVisitor builder = getDependencyVisitor(session, dependencyNodes::add);
-        DependencyFilter filter = request.getFilter();
-        DependencyVisitor visitor = (filter != null) ? new FilteringDependencyVisitor(builder, filter) : builder;
-        if (result.getRoot() != null) {
-            result.getRoot().accept(visitor);
-        }
+        final List<DependencyNode> dependencyNodes =
+                doFlattenDependencyNodes(session, result.getRoot(), request.getFilter());
 
         final List<ArtifactRequest> requests = dependencyNodes.stream()
                 .map(n -> {
@@ -302,12 +297,23 @@ public DependencyResult resolveDependencies(RepositorySystemSession session, Dep
     }
 
     @Override
-    public List<DependencyNode> flattenDependencyNodes(RepositorySystemSession session, DependencyNode root) {
+    public List<DependencyNode> flattenDependencyNodes(
+            RepositorySystemSession session, DependencyNode root, DependencyFilter dependencyFilter) {
         validateSession(session);
         requireNonNull(root, "root cannot be null");
 
+        return doFlattenDependencyNodes(session, root, dependencyFilter);
+    }
+
+    private List<DependencyNode> doFlattenDependencyNodes(
+            RepositorySystemSession session, DependencyNode root, DependencyFilter dependencyFilter) {
         final ArrayList<DependencyNode> dependencyNodes = new ArrayList<>();
-        root.accept(getDependencyVisitor(session, dependencyNodes::add));
+        if (root != null) {
+            DependencyVisitor builder = getDependencyVisitor(session, dependencyNodes::add);
+            DependencyVisitor visitor =
+                    (dependencyFilter != null) ? new FilteringDependencyVisitor(builder, dependencyFilter) : builder;
+            root.accept(visitor);
+        }
         return dependencyNodes;
     }