diff --git a/tests/v1/core/test_kv_cache_utils.py b/tests/v1/core/test_kv_cache_utils.py
index 8153fed699fe..08463a2800c2 100644
--- a/tests/v1/core/test_kv_cache_utils.py
+++ b/tests/v1/core/test_kv_cache_utils.py
@@ -43,7 +43,6 @@
     KVCacheGroupSpec,
     KVCacheSpec,
     KVCacheTensor,
-    MambaSpec,
     MLAAttentionSpec,
     SlidingWindowSpec,
     UniformTypeKVCacheSpecs,
@@ -158,24 +157,6 @@ def new_chunked_local_attention_spec(
     )
 
 
-def new_mamba_spec(
-    block_size=16,
-    shapes=((2, 512), (3, 32, 32)),
-    dtypes=(torch.float32, torch.float32),
-    num_speculative_blocks=2,
-    mamba_cache_mode="none",
-    page_size_padded=None,
-):
-    return MambaSpec(
-        block_size=block_size,
-        shapes=shapes,
-        dtypes=dtypes,
-        page_size_padded=page_size_padded,
-        mamba_cache_mode=mamba_cache_mode,
-        num_speculative_blocks=num_speculative_blocks,
-    )
-
-
 @pytest.mark.parametrize("hash_fn", [sha256, sha256_cbor])
 def test_none_hash(monkeypatch, hash_fn):
     import vllm.v1.core.kv_cache_utils
@@ -2029,28 +2010,6 @@ def test_auto_fit_max_model_len():
     assert vllm_config.model_config.max_model_len > 0
 
 
-def test_auto_fit_max_model_len_with_hybrid():
-    """Test that auto-fit works with hybrid KV cache specs."""
-    # Create config with original_max_model_len=-1 to trigger auto-fit
-    model_config = ModelConfig(max_model_len=8192)
-    # Simulate the user passing -1 by setting original_max_model_len
-    model_config.original_max_model_len = -1
-    vllm_config = VllmConfig(model_config=model_config)
-
-    mem_per_block_per_layer = 16 * 2 * 64 * 4 * 2  # 16KB per block per layer
-    gamma = 2
-    kv_cache_specs = {
-        "layer_1": new_mamba_spec(num_speculative_blocks=gamma),
-        "layer_2": new_kv_cache_spec(),
-    }
-
-    available_memory = mem_per_block_per_layer * (1024 // 16 + 1 + gamma)
-    _kv_cache_configs = get_kv_cache_configs(
-        vllm_config, [kv_cache_specs], [available_memory]
-    )
-    assert vllm_config.model_config.max_model_len == 1024
-
-
 def test_auto_fit_max_model_len_not_triggered():
     """Test that auto-fit is not triggered when original_max_model_len is not -1."""
     model_config = ModelConfig(max_model_len=16)
diff --git a/vllm/v1/core/kv_cache_utils.py b/vllm/v1/core/kv_cache_utils.py
index 83ada05309f9..3da3d7e7bef7 100644
--- a/vllm/v1/core/kv_cache_utils.py
+++ b/vllm/v1/core/kv_cache_utils.py
@@ -1356,10 +1356,8 @@ def _max_memory_usage_bytes_from_groups(
     page_size = get_uniform_page_size(
         [group.kv_cache_spec for group in kv_cache_groups]
     )
-    blocks_needed = sum(
-        cdiv(group.kv_cache_spec.max_memory_usage_bytes(vllm_config), page_size)
-        for group in kv_cache_groups
-    )
+    any_spec = kv_cache_groups[0].kv_cache_spec
+    blocks_needed = cdiv(any_spec.max_memory_usage_bytes(vllm_config), page_size)
 
     return group_size * page_size * blocks_needed