diff --git a/tests/test_torch2110_cuda_extras.py b/tests/test_torch2110_cuda_extras.py
index c110bad682..2ec0bb701c 100644
--- a/tests/test_torch2110_cuda_extras.py
+++ b/tests/test_torch2110_cuda_extras.py
@@ -11,12 +11,16 @@ Hermetic: only parses pyproject.toml, no network or install.
 
 from __future__ import annotations
 
-import tomllib
 from pathlib import Path
 
 import pytest
 from packaging.requirements import Requirement
 
+try:  # tomllib is stdlib on Python 3.11+; older interpreters need the tomli backport.
+    import tomllib
+except ModuleNotFoundError:  # pragma: no cover - Python 3.9 / 3.10
+    tomllib = pytest.importorskip("tomli")
+
 PYPROJECT = Path(__file__).resolve().parents[1] / "pyproject.toml"
 _TORCH_TRIO = ("torch", "torchvision", "torchaudio")
 
diff --git a/unsloth/_auto_install.py b/unsloth/_auto_install.py
index 13f5167856..396fa34d12 100644
--- a/unsloth/_auto_install.py
+++ b/unsloth/_auto_install.py
@@ -41,4 +41,8 @@ else: raise RuntimeError(f"Torch = {v} too new!")
 if v > V('2.6.9') and cuda not in ("11.8", "12.6", "12.8", "13.0"): raise RuntimeError(f"CUDA = {cuda} not supported!")
 if v >= V('2.10.0') and cuda not in ("12.6", "12.8", "13.0"): raise RuntimeError(f"Torch 2.10 requires CUDA 12.6, 12.8, or 13.0! Got CUDA = {cuda}")
 x = x.format(cuda.replace(".", ""), "-ampere" if False else "") # is_ampere is broken due to flash-attn
-print(f'pip install --upgrade pip setuptools wheel && pip install --no-deps git+https://github.com/unslothai/unsloth-zoo.git && pip install "unsloth[{x}] @ git+https://github.com/unslothai/unsloth.git" --no-build-isolation')
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+# The cu126/cu128 torch2110 extras pin torch==2.11.0+cuNNN, a local build that only
+# resolves from the matching PyTorch CUDA index (torch 2.11's default PyPI wheel is
+# CUDA 13.0), so add that index for exactly those CUDA-12 torch 2.11 environments.
+extra_index = f' --extra-index-url https://download.pytorch.org/whl/cu{cuda.replace(".", "")}' if (x.endswith('-torch2110') and cuda in ("12.6", "12.8")) else ''
+print(f'pip install --upgrade pip setuptools wheel && pip install --no-deps git+https://github.com/unslothai/unsloth-zoo.git && pip install "unsloth[{x}] @ git+https://github.com/unslothai/unsloth.git" --no-build-isolation{extra_index}')
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