diff --git a/auto_round/utils/missing_tensors.py b/auto_round/utils/missing_tensors.py
index 94f3d7be7..dd82c537b 100644
--- a/auto_round/utils/missing_tensors.py
+++ b/auto_round/utils/missing_tensors.py
@@ -617,6 +617,9 @@ def _update_qcfg(qcfg, show_log=True):
                     )
             if weight_keys:
                 existing = qcfg.get("block_name_to_quantize") or []
+                # In cases where this attribute is lacking
+                if not existing:
+                    return qcfg
                 if isinstance(existing, str):
                     existing = [b.strip() for b in existing.split(",") if b.strip()]
                 existing_set = set(existing)
diff --git a/test/test_cpu/utils/test_missing_tensors.py b/test/test_cpu/utils/test_missing_tensors.py
index 190404f86..a167ff908 100644
--- a/test/test_cpu/utils/test_missing_tensors.py
+++ b/test/test_cpu/utils/test_missing_tensors.py
@@ -248,8 +248,8 @@ class TestCopyMissingTensorsFromSource(unittest.TestCase):
     Special case: 'lm_head.weight' is always excluded.
     """
 
-    def _make_auto_round_config(self, bits=4, group_size=128, sym=True) -> dict:
-        return {
+    def _make_auto_round_config(self, bits=4, group_size=128, sym=True, block_name_to_quantize=None) -> dict:
+        qcfg = {
             "quantization_config": {
                 "quant_method": "auto-round",
                 "packing_format": "auto_round:auto_gptq",
@@ -258,6 +258,9 @@ def _make_auto_round_config(self, bits=4, group_size=128, sym=True) -> dict:
                 "sym": sym,
             }
         }
+        if block_name_to_quantize is not None:
+            qcfg["quantization_config"]["block_name_to_quantize"] = block_name_to_quantize
+        return qcfg
 
     # ------------------------------------------------------------------ #
     # Detection correctness                                                #
@@ -489,6 +492,34 @@ def test_block_name_to_ignore_not_quantized_in_woq_mode(self):
             self.assertIn("mtp.0.mlp.gate.weight", result)
             self.assertNotIn("mtp.0.mlp.gate.qweight", result)
 
+    def test_config_updated_without_block_name_to_quantize_after_woq(self):
+        """After WOQ, config.json is updated so the new block appears in block_name_to_quantize."""
+        out_features, in_features = 32, 128
+        with tempfile.TemporaryDirectory() as source_dir, tempfile.TemporaryDirectory() as target_dir:
+            _save_safetensors(
+                {"mtp.0.ffn.weight": torch.randn(out_features, in_features)},
+                os.path.join(source_dir, "model.safetensors"),
+            )
+            _save_safetensors(
+                {"model.embed_tokens.weight": torch.randn(8, 64)},
+                os.path.join(target_dir, "model.safetensors"),
+            )
+            raw_qcfg = self._make_auto_round_config(bits=4, group_size=128, sym=True)
+            with open(os.path.join(target_dir, "config.json"), "w") as f:
+                json.dump(raw_qcfg, f)
+
+            copy_missing_tensors_from_source(source_dir, target_dir)
+
+            with open(os.path.join(target_dir, "config.json")) as f:
+                updated_cfg = json.load(f)
+
+            qcfg = updated_cfg.get("quantization_config", {})
+            block_names = qcfg.get("block_name_to_quantize", [])
+            self.assertTrue(
+                block_names == [],
+                f"Expected no block_name_to_quantize, got: {block_names}",
+            )
+
     def test_config_updated_with_block_name_to_quantize_after_woq(self):
         """After WOQ, config.json is updated so the new block appears in block_name_to_quantize."""
         out_features, in_features = 32, 128
@@ -501,8 +532,11 @@ def test_config_updated_with_block_name_to_quantize_after_woq(self):
                 {"model.embed_tokens.weight": torch.randn(8, 64)},
                 os.path.join(target_dir, "model.safetensors"),
             )
+            raw_qcfg = self._make_auto_round_config(
+                bits=4, group_size=128, sym=True, block_name_to_quantize=["model.layers"]
+            )
             with open(os.path.join(target_dir, "config.json"), "w") as f:
-                json.dump(self._make_auto_round_config(bits=4, group_size=128, sym=True), f)
+                json.dump(raw_qcfg, f)
 
             copy_missing_tensors_from_source(source_dir, target_dir)