diff --git a/examples/misc/custom_projection.py b/examples/misc/custom_projection.py
index df2723df5a62..3994d0ffbd4a 100644
--- a/examples/misc/custom_projection.py
+++ b/examples/misc/custom_projection.py
@@ -374,12 +374,8 @@ class HammerAxes(GeoAxes):
     name = 'custom_hammer'
 
     class HammerTransform(Transform):
-        """
-        The base Hammer transform.
-        """
-        input_dims = 2
-        output_dims = 2
-        is_separable = False
+        """The base Hammer transform."""
+        input_dims = output_dims = 2
 
         def __init__(self, resolution):
             """
@@ -412,9 +408,7 @@ def inverted(self):
             return HammerAxes.InvertedHammerTransform(self._resolution)
 
     class InvertedHammerTransform(Transform):
-        input_dims = 2
-        output_dims = 2
-        is_separable = False
+        input_dims = output_dims = 2
 
         def __init__(self, resolution):
             Transform.__init__(self)
diff --git a/lib/matplotlib/projections/geo.py b/lib/matplotlib/projections/geo.py
index f9f5373b0172..e032d22ffe19 100644
--- a/lib/matplotlib/projections/geo.py
+++ b/lib/matplotlib/projections/geo.py
@@ -228,9 +228,7 @@ def drag_pan(self, button, key, x, y):
 
 class _GeoTransform(Transform):
     # Factoring out some common functionality.
-    input_dims = 2
-    output_dims = 2
-    is_separable = False
+    input_dims = output_dims = 2
 
     def __init__(self, resolution):
         """
diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
index 84212d4b726c..cde1be95f9e5 100644
--- a/lib/matplotlib/projections/polar.py
+++ b/lib/matplotlib/projections/polar.py
@@ -21,9 +21,7 @@ class PolarTransform(mtransforms.Transform):
     perform the ultimate affine transformation into the correct
     position.
     """
-    input_dims = 2
-    output_dims = 2
-    is_separable = False
+    input_dims = output_dims = 2
 
     def __init__(self, axis=None, use_rmin=True,
                  _apply_theta_transforms=True):
@@ -113,9 +111,7 @@ class InvertedPolarTransform(mtransforms.Transform):
     The inverse of the polar transform, mapping Cartesian
     coordinate space *x* and *y* back to *theta* and *r*.
     """
-    input_dims = 2
-    output_dims = 2
-    is_separable = False
+    input_dims = output_dims = 2
 
     def __init__(self, axis=None, use_rmin=True,
                  _apply_theta_transforms=True):
diff --git a/lib/mpl_toolkits/tests/test_axisartist_grid_helper_curvelinear.py b/lib/mpl_toolkits/tests/test_axisartist_grid_helper_curvelinear.py
index 3c9dd3a51731..bed21a64053c 100644
--- a/lib/mpl_toolkits/tests/test_axisartist_grid_helper_curvelinear.py
+++ b/lib/mpl_toolkits/tests/test_axisartist_grid_helper_curvelinear.py
@@ -20,9 +20,7 @@
                   tol={'aarch64': 0.034}.get(platform.machine(), 0.03))
 def test_custom_transform():
     class MyTransform(Transform):
-        input_dims = 2
-        output_dims = 2
-        is_separable = False
+        input_dims = output_dims = 2
 
         def __init__(self, resolution):
             """
@@ -48,9 +46,7 @@ def inverted(self):
             return MyTransformInv(self._resolution)
 
     class MyTransformInv(Transform):
-        input_dims = 2
-        output_dims = 2
-        is_separable = False
+        input_dims = output_dims = 2
 
         def __init__(self, resolution):
             Transform.__init__(self)