diff --git a/draco/core/containers.py b/draco/core/containers.py
index 0d8834bf..ccd5dea7 100644
--- a/draco/core/containers.py
+++ b/draco/core/containers.py
@@ -198,7 +198,7 @@ def __init__(self, *args, **kwargs):
                 copy_axis_attrs = False
 
                 # If axis is an integer, turn into an arange as a default definition
-                if isinstance(axis_map, int):
+                if isinstance(axis_map, (int, np.integer)):
                     axis_map = np.arange(axis_map)
 
             # If no valid map provided in arguments copy from another object if set