diff --git a/setup.cfg b/setup.cfg
index 447dca1..0dfcb70 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -7,7 +7,7 @@ url = https://github.com/fmi-faim/eicm.git
 author = Tim-Oliver Buchholz, Sabine Reither
 author_email = tim-oliver.buchholz@fmi.ch, sabine.reither@fmi.ch
 license = BSD-3-Clause
-license_file = LICENSE
+license_files = LICENSE
 classifiers =
     Development Status :: 3 - Alpha
     Intended Audience :: Developers
@@ -32,7 +32,7 @@ install_requires =
     scipy
     tifffile
     tqdm
-python_requires = >=3.8
+python_requires = >=3.9
 package_dir =
     =src
 setup_requires =
diff --git a/tests/test_gaussian2D_fit.py b/tests/test_gaussian2D_fit.py
index 7044798..cea9d99 100644
--- a/tests/test_gaussian2D_fit.py
+++ b/tests/test_gaussian2D_fit.py
@@ -36,10 +36,7 @@ def gaussian_2d(
             Shifts the Gaussian `up` or `down` i.e. the background signal.
     """
     return lambda y, x: offset + height * np.exp(
-        -(
-            ((y - mu_y) ** 2 / (2 * sigma_y**2))
-            + ((x - mu_x) ** 2 / (2 * sigma_x**2))
-        )
+        -(((y - mu_y) ** 2 / (2 * sigma_y**2)) + ((x - mu_x) ** 2 / (2 * sigma_x**2)))
     )