diff --git a/backends/cadence/aot/tests/test_quantizer_ops.py b/backends/cadence/aot/tests/test_quantizer_ops.py
index fa53c1818f5..66d61c5c5e3 100644
--- a/backends/cadence/aot/tests/test_quantizer_ops.py
+++ b/backends/cadence/aot/tests/test_quantizer_ops.py
@@ -64,6 +64,7 @@
 # Test case definitions for quantizer annotation tests.
 # Format: (name, graph_builder_fn, quantizer_instance, target_op, expected_output_qspec, expected_input_qspecs)
 # Adding a new quantizer test only requires adding a tuple to this list.
+# Note: Use None in expected_input_qspecs to skip comparison for that input (e.g., for DerivedQuantizationSpec).
 QUANTIZER_ANNOTATION_TEST_CASES: list[
     tuple[
         str,
@@ -71,7 +72,7 @@
         CadenceQuantizer,
         OpOverload,
         QuantizationSpec,
-        list[QuantizationSpec],
+        list[QuantizationSpec | None],
     ]
 ] = [
     (
@@ -192,6 +193,16 @@
         # For relu: only input_activation
         [qconfig_A8W8.input_activation],
     ),
+    (
+        "default_addmm_A8W8",
+        lambda self: self._build_addmm_graph(),
+        CadenceDefaultQuantizer(),
+        torch.ops.aten.addmm.default,
+        qconfig_A8W8.output_activation,
+        # For addmm: [bias (DerivedQuantizationSpec), mat1, mat2]
+        # Use None to skip comparison for bias since it's a DerivedQuantizationSpec
+        [None, qconfig_A8W8.input_activation, qconfig_A8W8.weight],
+    ),
 ]
 
 # Derive the set of tested quantizer classes from the test cases.
@@ -408,6 +419,31 @@ def _build_relu_graph(self) -> tuple[torch.fx.GraphModule, torch.fx.Node]:
         self.assertEqual(len(relu_nodes), 1, "Should find exactly one relu node")
         return gm, relu_nodes[0]
 
+    def _build_addmm_graph(self) -> tuple[torch.fx.GraphModule, torch.fx.Node]:
+        """Build a simple graph with an addmm operation."""
+        builder = GraphBuilder()
+        # addmm: bias + (mat1 @ mat2)
+        # args: (bias, mat1, mat2)
+        bias = builder.placeholder("bias", torch.randn(5))
+        mat1 = builder.placeholder("mat1", torch.randn(1, 10))
+        mat2 = builder.placeholder("mat2", torch.randn(10, 5))
+        addmm = builder.call_operator(
+            op=torch.ops.aten.addmm.default,
+            args=(bias, mat1, mat2),
+            meta=NodeMetadata(
+                {"source_fn_stack": [("addmm", torch.ops.aten.addmm.default)]}
+            ),
+        )
+        builder.output([addmm])
+        gm = builder.get_graph_module()
+
+        addmm_nodes = gm.graph.find_nodes(
+            op="call_function",
+            target=torch.ops.aten.addmm.default,
+        )
+        self.assertEqual(len(addmm_nodes), 1, "Should find exactly one addmm node")
+        return gm, addmm_nodes[0]
+
     @parameterized.expand(QUANTIZER_ANNOTATION_TEST_CASES)
     def test_quantizer_annotation(
         self,
@@ -416,7 +452,7 @@ def test_quantizer_annotation(
         quantizer: CadenceQuantizer,
         target: OpOverload,
         expected_output_qspec: QuantizationSpec,
-        expected_input_qspecs: list[QuantizationSpec],
+        expected_input_qspecs: list[QuantizationSpec | None],
     ) -> None:
         """Parameterized test for quantizer annotations."""
         gm, op_node = graph_builder_fn(self)
@@ -431,21 +467,24 @@ def test_quantizer_annotation(
 
         # Verify input annotations
         self.assertEqual(len(annotation.input_qspec_map), len(expected_input_qspecs))
-        for i, (input_node, input_qspec) in enumerate(
-            annotation.input_qspec_map.items()
-        ):
-            expected_arg = op_node.args[i]
-            assert isinstance(expected_arg, torch.fx.Node)
-            self.assertEqual(
-                input_node,
-                expected_arg,
-                f"Input node mismatch at index {i}",
-            )
-            self.assertEqual(
-                input_qspec,
-                expected_input_qspecs[i],
-                f"Input qspec mismatch at index {i}",
+        for input_node, input_qspec in annotation.input_qspec_map.items():
+            # Find the index of this input node in the op's args
+            arg_index = None
+            for i, arg in enumerate(op_node.args):
+                if arg is input_node:
+                    arg_index = i
+                    break
+            self.assertIsNotNone(
+                arg_index,
+                f"Input node {input_node} not found in op_node.args",
             )
+            # Skip comparison if expected qspec is None (e.g., for DerivedQuantizationSpec)
+            if expected_input_qspecs[arg_index] is not None:
+                self.assertEqual(
+                    input_qspec,
+                    expected_input_qspecs[arg_index],
+                    f"Input qspec mismatch at arg index {arg_index}",
+                )
 
     def test_all_quantizers_have_annotation_tests(self) -> None:
         """Ensure every CadenceQuantizer subclass is either tested or explicitly excluded."""