diff --git a/arraycontext/container/traversal.py b/arraycontext/container/traversal.py
index ff64e643..c2c05bf5 100644
--- a/arraycontext/container/traversal.py
+++ b/arraycontext/container/traversal.py
@@ -1095,8 +1095,9 @@ def _flat_size(subary: ArrayOrContainerOrScalar) -> Array | int | np.integer:
         try:
             iterable = serialize_container(subary)
         except NotAnArrayContainerError:
-            assert not is_array_container(subary)
-            assert not is_scalar_like(subary)
+            if TYPE_CHECKING:
+                assert not is_array_container(subary)
+                assert not is_scalar_like(subary)
 
             if common_dtype is None:
                 common_dtype = subary.dtype
diff --git a/arraycontext/impl/jax/fake_numpy.py b/arraycontext/impl/jax/fake_numpy.py
index 3ae7f9c6..b96607e5 100644
--- a/arraycontext/impl/jax/fake_numpy.py
+++ b/arraycontext/impl/jax/fake_numpy.py
@@ -123,7 +123,7 @@ def inner_bcast(ary: ArrayOrScalar) -> ArrayOrScalar:
             if is_scalar_like(ary):
                 return ary
             else:
-                assert isinstance(ary, np.ndarray)
+                assert isinstance(ary, jnp.ndarray)
                 return cast("Array", cast("object", jnp.broadcast_to(ary, shape)))
 
         return rec_map_container(inner_bcast, array)
@@ -145,7 +145,7 @@ def vdot(self, a, b, dtype=None):
         from arraycontext import rec_multimap_reduce_array_container
 
         def _rec_vdot(ary1, ary2):
-            common_dtype = np.result_type(ary1, ary2)
+            common_dtype = jnp.result_type(ary1, ary2)
             if dtype not in (None, common_dtype):
                 raise NotImplementedError(
                     f"{type(self).__name__} cannot take dtype in vdot.")
diff --git a/arraycontext/impl/pytato/__init__.py b/arraycontext/impl/pytato/__init__.py
index 7c667a79..a8ec6def 100644
--- a/arraycontext/impl/pytato/__init__.py
+++ b/arraycontext/impl/pytato/__init__.py
@@ -829,7 +829,7 @@ def transform_dag(self, dag: pytato.AbstractResultWithNamedArrays
         import pytato as pt
         dag = pt.tag_all_calls_to_be_inlined(dag)
         dag = pt.inline_calls(dag)
-        return pt.transform.materialize_with_mpms(dag)
+        return pt.materialize_with_mpms(dag)
 
     @override
     def einsum(self, spec, *args, arg_names=None, tagged=()):
diff --git a/test/test_arraycontext.py b/test/test_arraycontext.py
index de143985..e5336cc2 100644
--- a/test/test_arraycontext.py
+++ b/test/test_arraycontext.py
@@ -676,7 +676,7 @@ def test_array_context_csr_matmul(actx_factory: ArrayContextFactory):
         momentum=obj_array.new_1d([x] * 3),
         enthalpy=x)
 
-    elem_values = actx.zeros((n//2,), dtype=np.float64) + 1.
+    elem_values = actx.np.zeros((n//2,), dtype=np.float64) + 1.
     elem_col_indices = actx.from_numpy(2*np.arange(n//2, dtype=np.int32))
     row_starts = actx.from_numpy(np.arange(n//2 + 1, dtype=np.int32))