diff --git a/tf_adapter/optimizers/control_flow_conversion_pass.cc b/tf_adapter/optimizers/control_flow_conversion_pass.cc
index 0f1e33c2a6e047cdb0a2e715b891b85b195b6be6..c6d7c9afe324e6c5151fe4e518d0315b6f8aae9b 100644
--- a/tf_adapter/optimizers/control_flow_conversion_pass.cc
+++ b/tf_adapter/optimizers/control_flow_conversion_pass.cc
@@ -69,6 +69,7 @@ Status ControlFlowConversionPass::Run(const GraphOptimizationPassOptions &option
   // Delete _lower_using_switch_merge before LowerFunctionalOpsPass
   for (int i = 2; i < graph->num_node_ids(); ++i) {
     Node *n = graph->FindNodeId(i);
+    if (n == nullptr) { continue; }
     if (n->IsIfNode() || n->type_string() == "Case" || n->IsWhileNode()) { n->ClearAttr(kLowerUsingSwitchMergeAttr); }
   }