diff --git a/src/AnimGraphResource.cc b/src/AnimGraphResource.cc
index 61f6112..fecf245 100644
--- a/src/AnimGraphResource.cc
+++ b/src/AnimGraphResource.cc
@@ -389,11 +389,15 @@ void AnimGraph::UpdateOrderedNodes() {
 void AnimGraph::MarkActiveNodes() {
   m_frame_counter++;
 
-  int first_node_index = getAnimNodeIndex(m_ordered_nodes[0]);
-  m_ordered_nodes[0]->m_frame_counter = m_frame_counter;
-  m_ordered_nodes[0]->UpdateActiveInputFrameCounters(m_node_inputs[first_node_index]);
+  const std::vector<AnimNodeInput> graph_output_inputs = m_node_inputs[0];
+  for (size_t i = 0, n = graph_output_inputs.size(); i < n; i++) {
+    AnimNode* node = m_ordered_nodes[i];
+    if (node != nullptr) {
+      node->m_frame_counter = m_frame_counter;
+    }
+  }
 
-  for (size_t i = 1, n = m_ordered_nodes.size(); i < n; i++) {
+  for (size_t i = 0, n = m_ordered_nodes.size(); i < n; i++) {
     AnimNode* node = m_ordered_nodes[i];
     if (CheckIsNodeActive(node)) {
       int node_index = getAnimNodeIndex(node);