diff --git a/imops/src/_backprojection.pyx b/imops/src/_backprojection.pyx
index 5e8f6163..ecb927fd 100644
--- a/imops/src/_backprojection.pyx
+++ b/imops/src/_backprojection.pyx
@@ -53,8 +53,8 @@ cdef FLOAT accumulate(FLOAT x, FLOAT y, const FLOAT* sinuses, const FLOAT* cosin
 @cython.boundscheck(False)
 @cython.wraparound(False)
 cpdef FLOAT[:, :, :] backprojection3d(const FLOAT[:, :, :] sinogram, const FLOAT[:] theta, FLOAT[:] xs,
-                                      const uint8[:, :] inside_circle, FLOAT fill_value, int image_size, int output_size,
-                                      Py_ssize_t num_threads):
+                                      const uint8[:, :] inside_circle, FLOAT fill_value, int image_size,
+                                      int output_size, Py_ssize_t num_threads):
     cdef FLOAT[:, :, :] result = np.zeros_like(sinogram, shape=(len(sinogram), output_size, output_size))
     cdef Py_ssize_t slc, i, j, n_angles = len(theta), n_slices = len(sinogram)
     cdef FLOAT min_val = image_size // 2, right_lim = image_size - 1
diff --git a/imops/src/_measure.pyx b/imops/src/_measure.pyx
index 66019383..e842be0b 100644
--- a/imops/src/_measure.pyx
+++ b/imops/src/_measure.pyx
@@ -33,7 +33,8 @@ cdef inline Py_ssize_t _find(LABEL num, const LABEL[:] nums) noexcept nogil:
     return -1
 
 
-def _labeled_center_of_mass(const double[:, :, :] nums, const LABEL[:, :, :] labels, const LABEL[:] index) -> np.ndarray:
+def _labeled_center_of_mass(const double[:, :, :] nums, const LABEL[:, :, :] labels,
+                            const LABEL[:] index) -> np.ndarray:
     cdef const double[:, :, ::1] contiguous_nums = np.ascontiguousarray(nums)
     cdef const LABEL[:, :, ::1] contiguous_labels = np.ascontiguousarray(labels)
     cdef const LABEL[:] contiguous_index = np.ascontiguousarray(index)
diff --git a/tests/test_morphology.py b/tests/test_morphology.py
index 9914908d..071f9a8b 100644
--- a/tests/test_morphology.py
+++ b/tests/test_morphology.py
@@ -14,9 +14,9 @@
 from imops.backend import Backend, Scipy
 from imops.morphology import binary_closing, binary_dilation, binary_erosion, binary_opening, distance_transform_edt
 from imops.pad import restore_crop
-
 from imops.utils import make_immutable
 
+
 np.random.seed(1337)
 
 assert_eq = np.testing.assert_array_equal
diff --git a/tests/test_radon.py b/tests/test_radon.py
index 2c2c1a2f..9cb6d790 100644
--- a/tests/test_radon.py
+++ b/tests/test_radon.py
@@ -8,7 +8,7 @@
 from imops.backend import Backend
 from imops.radon import inverse_radon, radon
 from imops.testing import fill_outside, sample_ct, sk_iradon, sk_radon
-from imops.utils import make_immutable, make_mutable
+from imops.utils import make_immutable
 
 
 np.random.seed(1337)
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 0b782f46..45adfe6d 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -13,6 +13,7 @@
     imops_num_threads,
     isin,
     make_immutable,
+    make_mutable,
     normalize_num_threads,
     set_num_threads,
 )