diff --git a/tests/unit/test_use_attn_result.py b/tests/unit/test_use_attn_result.py
new file mode 100644
index 000000000..417374f59
--- /dev/null
+++ b/tests/unit/test_use_attn_result.py
@@ -0,0 +1,73 @@
+import torch
+
+from transformer_lens import HookedTransformer
+from transformer_lens.HookedTransformerConfig import HookedTransformerConfig
+
+
+def test_atten_result_normal_attn_correct():
+    """Verifies that the attn_result flag does not change the output for models with normal attention."""
+    d_model = 128
+    d_head = 8
+    n_heads = 16
+    n_ctx = 128
+    n_layers = 1
+    d_vocab = 10
+
+    cfg = HookedTransformerConfig(
+        d_model=d_model,
+        d_head=d_head,
+        n_heads=n_heads,
+        n_ctx=n_ctx,
+        n_layers=n_layers,
+        attn_only=True,
+        d_vocab=d_vocab,
+    )
+
+    model = HookedTransformer(cfg)
+    assert model.cfg.use_split_qkv_input is False
+
+    x = torch.arange(1, 9).unsqueeze(0)
+    normal_output = model(x)
+
+    model.set_use_attn_result(True)
+    assert model.cfg.use_attn_result is True
+
+    split_output = model(x)
+
+    assert torch.allclose(normal_output, split_output, atol=1e-6)
+
+
+def test_atten_result_grouped_query_attn_correct():
+    """Verifies that the atten_result flag does not change the output for models with grouped query attention."""
+
+    d_model = 128
+    d_head = 8
+    n_heads = 16
+    n_ctx = 128
+    n_key_value_heads = 2
+    n_layers = 1
+    d_vocab = 10
+
+    cfg = HookedTransformerConfig(
+        d_model=d_model,
+        d_head=d_head,
+        n_heads=n_heads,
+        n_ctx=n_ctx,
+        n_key_value_heads=n_key_value_heads,
+        n_layers=n_layers,
+        attn_only=True,
+        d_vocab=d_vocab,
+    )
+
+    model = HookedTransformer(cfg)
+    assert model.cfg.use_split_qkv_input is False
+
+    x = torch.arange(1, 9).unsqueeze(0)
+    normal_output = model(x)
+
+    model.set_use_attn_result(True)
+    assert model.cfg.use_attn_result is True
+
+    split_output = model(x)
+
+    assert torch.allclose(normal_output, split_output, atol=1e-6)
diff --git a/transformer_lens/HookedTransformer.py b/transformer_lens/HookedTransformer.py
index 8ee2e74f8..8e32a9cd6 100644
--- a/transformer_lens/HookedTransformer.py
+++ b/transformer_lens/HookedTransformer.py
@@ -8,7 +8,6 @@
 alteration of activations in individual components like attention heads and MLP layers, facilitating
 a deeper understanding of the internal workings of transformers like GPT-2.
 """
-
 import logging
 import os
 from typing import Dict, List, NamedTuple, Optional, Tuple, Union, cast, overload
@@ -1570,7 +1569,10 @@ def load_and_process_state_dict(
             # so that quantization settings are not lost
             self.load_state_dict(state_dict, assign=True, strict=False)
         else:
-            self.load_state_dict(state_dict, strict=False)
+            state_dict_keys = list(state_dict.keys())
+            for key in state_dict_keys:
+                self.load_state_dict({key: state_dict[key]}, strict=False)
+                del state_dict[key]
 
     def fill_missing_keys(self, state_dict):
         return loading.fill_missing_keys(self, state_dict)