diff --git a/.github/workflows/pytest.yaml b/.github/workflows/pytest.yaml
index 7c68b65..57deb25 100644
--- a/.github/workflows/pytest.yaml
+++ b/.github/workflows/pytest.yaml
@@ -66,7 +66,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --progress-bar off --upgrade pip setuptools
-          python -m pip install --progress-bar off .[test]
+          python -m pip install --progress-bar off --no-cache-dir .[test]
           python -m pip install matplotlib
           python -m pip install --progress-bar off --upgrade --no-deps --pre --only-binary :all: -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple --timeout=180 matplotlib
           python -m pip install --progress-bar off --upgrade --pre --only-binary :all: -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple --timeout=180 numpy scipy
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 800ec80..9172e81 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -25,7 +25,6 @@ repos:
       hooks:
           - id: codespell
 
-
     - repo: https://github.com/astral-sh/ruff-pre-commit
       rev: v0.12.2
       hooks:
diff --git a/nigsp/tests/test_io.py b/nigsp/tests/test_io.py
index b45b21f..7529ae4 100644
--- a/nigsp/tests/test_io.py
+++ b/nigsp/tests/test_io.py
@@ -8,7 +8,7 @@
 import nibabel
 import pymatreader
 import scipy
-from numpy import asarray, empty, genfromtxt, savetxt
+from numpy import asarray, empty, genfromtxt, ones, savetxt
 from numpy.random import rand
 from pytest import mark, raises
 
@@ -123,7 +123,7 @@ def test_export_nifti(atlas):
     """Test export_nifti."""
     img = nibabel.load(atlas)
     shape = img.get_fdata().shape
-    io.export_nifti(empty(shape), img, "book")
+    io.export_nifti(ones(shape), img, "book")
     assert isfile("book.nii.gz")
     remove("book.nii.gz")
     remove(atlas)
diff --git a/pyproject.toml b/pyproject.toml
index c7ffeda..602b392 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,7 +21,7 @@ omit = [
 [tool.ruff]
 extend-exclude = ['docs', 'versioneer.py', 'setup.py']
 line-length = 88
-target-version = 'py37'
+target-version = 'py38'
 
 [tool.ruff.format]
 docstring-code-format = true