diff --git a/.github/workflows/build_windows.yml b/.github/workflows/build_windows.yml
index 68bf05a60..83179172b 100644
--- a/.github/workflows/build_windows.yml
+++ b/.github/workflows/build_windows.yml
@@ -26,6 +26,10 @@ jobs:
         pip install -r requirements.txt
         pip install wheel twine
 
+    - name: Update numpy for python 3.10 only
+      if: ${{ matrix.python-version == '3.10'}}
+      run: pip install numpy --upgrade
+
     - name: Compile library
       run: |
         cd aequilibrae/paths
diff --git a/aequilibrae/distribution/gravity_calibration.py b/aequilibrae/distribution/gravity_calibration.py
index 92f6300d8..6344cbe91 100644
--- a/aequilibrae/distribution/gravity_calibration.py
+++ b/aequilibrae/distribution/gravity_calibration.py
@@ -218,15 +218,13 @@ def __check_inputs(self):
         mats = [(self.matrix, "Observed matrix"), (self.impedance, "Impedance matrix")]
         for matrix, title in mats:
             if matrix.matrix_view is None:
-                raise ValueError(title + " needs to be set for computation")
-            else:
-                if len(matrix.matrix_view.shape[:]) > 2:
-                    raise ValueError(title + "' computational view needs to be set for a single matrix core")
-
+                raise ValueError(f"{title} needs to be set for computation")
+            if matrix.matrix_view.ndim > 2:
+                raise ValueError(f"{title} computational view needs to be set for a single matrix core")
             if np.nansum(matrix.matrix_view.data) == 0:
-                raise ValueError(title + "has only zero values")
+                raise ValueError(f"{title} has only zero values")
             if np.nanmin(matrix.matrix_view.data) < 0:
-                raise ValueError(title + "has negative values")
+                raise ValueError(f"{title} has negative values")
 
         # Augment parameters if we happen to have only passed one
         default_parameters = self.__get_parameters()
diff --git a/aequilibrae/matrix/aequilibrae_matrix.py b/aequilibrae/matrix/aequilibrae_matrix.py
index 7fbb5572b..cb6cd30c6 100644
--- a/aequilibrae/matrix/aequilibrae_matrix.py
+++ b/aequilibrae/matrix/aequilibrae_matrix.py
@@ -1021,8 +1021,7 @@ def nan_to_num(self):
             raise NotImplementedError("This operation does not make sense for OMX matrices")
 
         if np.issubdtype(self.dtype, np.floating) and self.matrix_view is not None:
-            for m in self.view_names:
-                self.matrix[m][:, :] = np.nan_to_num(self.matrix[m])[:, :]
+            self.matrices[:, :, :] = np.nan_to_num(self.matrices[:, :, :])
 
     def __vector(self, axis: int):
         if self.view_names is None:
diff --git a/tests/aequilibrae/distribution/test_gravityApplication.py b/tests/aequilibrae/distribution/test_gravityApplication.py
index 188ec647e..31c8e16f9 100644
--- a/tests/aequilibrae/distribution/test_gravityApplication.py
+++ b/tests/aequilibrae/distribution/test_gravityApplication.py
@@ -38,7 +38,7 @@
 matrix.create_empty(**args)
 
 # randoms = np.random.randint(5, size=(2, 4))
-matrix.impedance[:, :] = np.random.rand(zones, zones)[:, :]
+matrix.matrices[:, :, 0] = np.random.rand(zones, zones)[:, :]
 matrix.index[:] = np.arange(matrix.zones) + 100
 matrix.computational_view(["impedance"])
 
diff --git a/tests/aequilibrae/distribution/test_gravityCalibration.py b/tests/aequilibrae/distribution/test_gravityCalibration.py
index 6f5ac650d..5480ccb43 100644
--- a/tests/aequilibrae/distribution/test_gravityCalibration.py
+++ b/tests/aequilibrae/distribution/test_gravityCalibration.py
@@ -16,7 +16,7 @@
 
 impedance = AequilibraeMatrix()
 impedance.create_empty(**args)
-impedance.impedance[:, :] = np.random.rand(zones, zones)[:, :] * 1000
+impedance.matrices[:, :, 0] = np.random.rand(zones, zones) * 1000
 impedance.index[:] = np.arange(impedance.zones) + 100
 impedance.computational_view(["impedance"])
 
@@ -24,7 +24,7 @@
 args["file_name"] = AequilibraeMatrix().random_name()
 matrix = AequilibraeMatrix()
 matrix.create_empty(**args)
-matrix.base_matrix[:, :] = np.random.rand(zones, zones)[:, :] * 1000
+matrix.matrices[:, :, 0] = np.random.rand(zones, zones) * 1000
 matrix.index[:] = np.arange(matrix.zones) + 100
 matrix.computational_view(["base_matrix"])
 
diff --git a/tests/aequilibrae/matrix/test_aequilibraeMatrix.py b/tests/aequilibrae/matrix/test_aequilibraeMatrix.py
index 76706834e..234a2d72e 100644
--- a/tests/aequilibrae/matrix/test_aequilibraeMatrix.py
+++ b/tests/aequilibrae/matrix/test_aequilibraeMatrix.py
@@ -41,8 +41,8 @@ def setUp(self) -> None:
         self.matrix.create_empty(**args)
 
         self.matrix.index[:] = np.arange(self.matrix.zones) + 100
-        self.matrix.mat[:, :] = np.random.rand(self.matrix.zones, self.matrix.zones)[:, :]
-        self.matrix.mat[:, :] = self.matrix.mat[:, :] * (1000 / np.sum(self.matrix.mat[:, :]))
+        self.matrix.matrices[:, :, 0] = np.random.rand(self.matrix.zones, self.matrix.zones)
+        self.matrix.matrices[:, :, 0] = self.matrix.mat * (1000 / np.sum(self.matrix.mat))
         self.matrix.setName("Test matrix - " + str(random.randint(1, 10)))
         self.matrix.setDescription("Generated at " + datetime.datetime.now().strftime("%I:%M%p on %B %d, %Y"))
         self.new_matrix = self.matrix
@@ -141,7 +141,7 @@ def test_nan_to_num(self):
         m = self.new_matrix.mat.sum() - self.new_matrix.mat[1, 1]
         self.new_matrix.computational_view(["mat", "seed"])
         self.new_matrix.nan_to_num()
-        self.new_matrix.mat[1, 1] = np.nan
+        self.new_matrix.matrices[1, 1, 0] = np.nan
         self.new_matrix.computational_view(["mat"])
         self.new_matrix.nan_to_num()
 
@@ -266,7 +266,7 @@ def test_matrix_reference_doesnt_prevent_resource_cleanup(tmp_path):
     }
     matrix = AequilibraeMatrix()
     matrix.create_empty(**kwargs)
-    ref = matrix.mat
+    _ = matrix.mat
     del matrix
 
     try: