diff --git a/jaxtyping/__init__.py b/jaxtyping/__init__.py
index eae9389..34cd945 100644
--- a/jaxtyping/__init__.py
+++ b/jaxtyping/__init__.py
@@ -63,4 +63,4 @@ from .import_hook import install_import_hook
 from .pytree_type import PyTree
 
 
-__version__ = "0.2.3"
+__version__ = "0.2.4"
diff --git a/jaxtyping/array_types.py b/jaxtyping/array_types.py
index 22dea71..3a91678 100644
--- a/jaxtyping/array_types.py
+++ b/jaxtyping/array_types.py
@@ -150,14 +150,15 @@ class _MetaAbstractArray(type):
         if cls.dtypes is not _any_dtype and dtype not in cls.dtypes:
             return False
 
-        if len(storage.memo_stack) == 0:
+        temp_memo = not hasattr(storage, "memo_stack") or len(storage.memo_stack) == 0
+
+        if temp_memo:
             # `isinstance` happening outside any @jaxtyped decorators, e.g. at the
             # global scope. In this case just create a temporary memo, since we're not
             # going to be comparing against any stored values anyway.
             single_memo = {}
             variadic_memo = {}
             variadic_broadcast_memo = {}
-            temp_memo = True
         else:
             single_memo, variadic_memo, variadic_broadcast_memo = storage.memo_stack[-1]
             # Make a copy so we don't mutate the original memo during the shape check.
@@ -474,7 +475,10 @@ else:
 
         _Cls.__name__ = name
         _Cls.__qualname__ = name
-        _Cls.__module__ = "jaxtyping"
+        if getattr(typing, "GENERATING_DOCUMENTATION", False):
+            _Cls.__module__ = "builtins"
+        else:
+            _Cls.__module__ = "jaxtyping"
         return _Cls
 
     UInt8 = _make_dtype(_uint8, "UInt8")
diff --git a/jaxtyping/pytree_type.py b/jaxtyping/pytree_type.py
index 38a7008..b97a208 100644
--- a/jaxtyping/pytree_type.py
+++ b/jaxtyping/pytree_type.py
@@ -18,7 +18,9 @@
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 import functools as ft
-from typing import Generic, TypeVar
+import typing
+from typing import Generic, TYPE_CHECKING, TypeVar
+from typing_extensions import Protocol
 
 import jax
 import typeguard
@@ -51,7 +53,10 @@ class _MetaPyTree(type):
     def __getitem__(cls, item):
         name = str(_FakePyTree[item])
         out = _MetaSubscriptPyTree(name, (), {"leaftype": item})
-        out.__module__ = "jaxtyping"
+        if getattr(typing, "GENERATING_DOCUMENTATION", False):
+            out.__module__ = "builtins"
+        else:
+            out.__module__ = "jaxtyping"
         return out
 
 
@@ -82,8 +87,18 @@ class _MetaSubscriptPyTree(type):
         return all(map(is_leaftype, leaves))
 
 
-PyTree = _MetaPyTree("PyTree", (), {})
-PyTree.__module__ = "jaxtyping"
+if TYPE_CHECKING:
+    # Work around pytype bug #1288
+    # pytype: skip-file
+    class PyTree(Protocol[_T]):
+        pass
+
+else:
+    PyTree = _MetaPyTree("PyTree", (), {})
+    if getattr(typing, "GENERATING_DOCUMENTATION", False):
+        PyTree.__module__ = "builtins"
+    else:
+        PyTree.__module__ = "jaxtyping"
 # Can't do `class PyTree(Generic[_T]): ...` because we need to override the
-# instancecheck for PyTree[foo], but we subclassing
+# instancecheck for PyTree[foo], but subclassing
 # `type(Generic[int])`, i.e. `typing._GenericAlias` is disallowed.
diff --git a/test/test_threading.py b/test/test_threading.py
index 24c50b3..557fba7 100644
--- a/test/test_threading.py
+++ b/test/test_threading.py
@@ -25,7 +25,22 @@ from typeguard import typechecked
 from jaxtyping import Array, Float, jaxtyped
 
 
-def test_threading():
+class _ErrorableThread(threading.Thread):
+    def run(self):
+        try:
+            super().run()
+        except Exception as e:
+            self.exc = e
+        finally:
+            del self._target, self._args, self._kwargs
+
+    def join(self, timeout=None):
+        super().join(timeout)
+        if hasattr(self, "exc"):
+            raise self.exc
+
+
+def test_threading_jaxtyped():
     @jaxtyped
     @typechecked
     def add(x: Float[Array, "a b"], y: Float[Array, "a b"]) -> Float[Array, "a b"]:
@@ -36,6 +51,16 @@ def test_threading():
         b = jnp.array([[2.0, 3.0]])
         add(a, b)
 
-    thread = threading.Thread(target=run)
+    thread = _ErrorableThread(target=run)
+    thread.start()
+    thread.join()
+
+
+def test_threading_nojaxtyped():
+    def run():
+        a = jnp.array([[1.0, 2.0]])
+        assert isinstance(a, Float[Array, "..."])
+
+    thread = _ErrorableThread(target=run)
     thread.start()
     thread.join()