diff --git a/mlprodict/onnxrt/ops_cpu/op_cum_sum.py b/mlprodict/onnxrt/ops_cpu/op_cum_sum.py
index ab8532dee..53e8013da 100644
--- a/mlprodict/onnxrt/ops_cpu/op_cum_sum.py
+++ b/mlprodict/onnxrt/ops_cpu/op_cum_sum.py
@@ -26,19 +26,23 @@ def _run(self, x, *axis):  # pylint: disable=W0221
                     'reverse=1 or exclusive=1 not implemented')
             if self.inplaces.get(0, False):
                 return (numpy.cumsum(x, out=x), )
-            else:
-                return (numpy.cumsum(x), )
-        if len(axis.shape) != 1 or axis.shape[0] != 1:
-            raise RuntimeError(
-                "axis must be an array of one number not {}".format(axis))
-        axis = axis[0]
+            return (numpy.cumsum(x), )
+        if isinstance(axis, (numpy.int32, numpy.int64)):
+            pass
+        else:
+            if (len(axis.shape) > 1 or (len(axis.shape) > 0 and
+                    axis.shape[0] != 1)):
+                raise RuntimeError(
+                    "axis must be an array of one number not {} "
+                    "(shape {})".format(axis, axis.shape))
+            if len(axis.shape) > 0:
+                axis = axis[0]
         if self.reverse or self.exclusive:
             raise NotImplementedError(
                 'reverse=1 or exclusive=1 not implemented')
         if self.inplaces.get(0, False):
             return (numpy.cumsum(x, axis=axis, out=x), )
-        else:
-            return (numpy.cumsum(x, axis=axis), )
+        return (numpy.cumsum(x, axis=axis), )
 
     def _infer_shapes(self, x, *axis):  # pylint: disable=W0221
         return (x, )