diff --git a/arraycontext/fake_numpy.py b/arraycontext/fake_numpy.py
index 7e9b189ca1c7fa6491b79d07bb77e6de4e71e840..e5c281c415fad36cd838f71186b6373354160603 100644
--- a/arraycontext/fake_numpy.py
+++ b/arraycontext/fake_numpy.py
@@ -196,6 +196,7 @@ class BaseFakeNumpyLinalgNamespace:
             ord = 2
 
         from arraycontext.impl import _is_meshmode_dofarray
+        from arraycontext.impl.pyopencl import _flatten_array
 
         if _is_meshmode_dofarray(ary):
             from warnings import warn
diff --git a/arraycontext/impl/pyopencl.py b/arraycontext/impl/pyopencl.py
index d0777a6c73dd201c1022426be94bc7e2912fe513..0e6f8d950f4067afb27cbf2b4e7490c86707f844 100644
--- a/arraycontext/impl/pyopencl.py
+++ b/arraycontext/impl/pyopencl.py
@@ -39,7 +39,6 @@ from arraycontext.metadata import FirstAxisIsElementsTag
 from arraycontext.fake_numpy import \
         BaseFakeNumpyNamespace, BaseFakeNumpyLinalgNamespace
 from arraycontext.container.traversal import rec_multimap_array_container
-from arraycontext.container import serialize_container
 from arraycontext.context import ArrayContext
 
 
diff --git a/arraycontext/impl/pytato.py b/arraycontext/impl/pytato.py
index ebc69df538a31c4ec50ea135a0064dd7f993a8a6..552fc9feec533ba00065911cd6b9e61fd56248c8 100644
--- a/arraycontext/impl/pytato.py
+++ b/arraycontext/impl/pytato.py
@@ -288,7 +288,8 @@ class PytatoArrayContext(ArrayContext):
         if isinstance(array, cla.Array):
             return array.with_queue(None)
         if not isinstance(array, pt.Array):
-            raise TypeError(f"PytatoArrayContext.freeze invoked with non-pt array of type '{type(array)}'")
+            raise TypeError("PytatoArrayContext.freeze invoked with non-pt "
+                            f"array of type '{type(array)}'")
 
         prg = pt.generate_loopy(array, cl_device=self.queue.device)
         evt, (cl_array,) = prg(self.queue)