diff --git a/patsy/design_info.py b/patsy/design_info.py
index 2757f0a..435f2de 100644
--- a/patsy/design_info.py
+++ b/patsy/design_info.py
@@ -471,7 +471,7 @@ def slice(self, columns_specifier):
         """
         if isinstance(columns_specifier, slice):
             return columns_specifier
-        if np.issubsctype(type(columns_specifier), np.integer):
+        if np.issubdtype(type(columns_specifier), np.integer):
             return slice(columns_specifier, columns_specifier + 1)
         if (self.term_slices is not None
             and columns_specifier in self.term_slices):