diff --git a/qiskit/transpiler/passes/synthesis/high_level_synthesis.py b/qiskit/transpiler/passes/synthesis/high_level_synthesis.py
index 87d953e27f8..d7b5b0d535b 100644
--- a/qiskit/transpiler/passes/synthesis/high_level_synthesis.py
+++ b/qiskit/transpiler/passes/synthesis/high_level_synthesis.py
@@ -382,7 +382,7 @@ def _run(
 
             # If the synthesis changed the operation (i.e. it is not None), store the result.
             if synthesized is not None:
-                synthesized_nodes[node] = (synthesized, synthesized_context)
+                synthesized_nodes[node._node_id] = (synthesized, synthesized_context)
 
             # If the synthesis did not change anything, just update the qubit tracker.
             elif not processed:
@@ -407,8 +407,9 @@ def _run(
         outer_to_local = context.to_local_mapping()
 
         for node in dag.topological_op_nodes():
-            if node in synthesized_nodes:
-                op, op_context = synthesized_nodes[node]
+
+            if op_tuple := synthesized_nodes.get(node._node_id, None):
+                op, op_context = op_tuple
 
                 if isinstance(op, Operation):
                     out.apply_operation_back(op, node.qargs, node.cargs)