diff --git a/skimage/transform/_geometric.py b/skimage/transform/_geometric.py
index 6c0afbdb..cfa12033 100644
--- a/skimage/transform/_geometric.py
+++ b/skimage/transform/_geometric.py
@@ -954,9 +954,10 @@ def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
     # use fast Cython version for specific interpolation orders
     if order in range(4) and not map_args:
         matrix = None
-        if isinstance(inverse_map, HOMOGRAPHY_TRANSFORMS):
+        if inverse_map in HOMOGRAPHY_TRANSFORMS:
             matrix = inverse_map._matrix
-        elif inverse_map.__name__ == 'inverse' \
+        elif hasattr(inverse_map, '__name__') \
+                and inverse_map.__name__ == 'inverse' \
                 and inverse_map.im_class in HOMOGRAPHY_TRANSFORMS:
             matrix = np.linalg.inv(inverse_map.im_self._matrix)
         if matrix is not None: