diff --git a/core/superduperreload/__init__.py b/core/superduperreload/__init__.py
index b09c47f..d98ee6f 100644
--- a/core/superduperreload/__init__.py
+++ b/core/superduperreload/__init__.py
@@ -11,7 +11,7 @@
 __version__ = _version.get_versions()['version']
 
 
-def make_autoreload_magics(shell: "InteractiveShell", enable_file_watching: bool = True) -> AutoreloadMagics:
+def make_autoreload_magics(shell: "InteractiveShell") -> AutoreloadMagics:
     try:
         from ipyflow import flow
 
@@ -19,7 +19,7 @@ def make_autoreload_magics(shell: "InteractiveShell", enable_file_watching: bool
     except:
         flow_ = None
 
-    return AutoreloadMagics(shell, flow=flow_, enable_file_watching=enable_file_watching)
+    return AutoreloadMagics(shell, flow=flow_)
 
 
 def load_ipython_extension(ip: "InteractiveShell", magics: Optional[AutoreloadMagics] = None) -> None:
diff --git a/core/superduperreload/magics.py b/core/superduperreload/magics.py
index d9c9543..d75de4c 100644
--- a/core/superduperreload/magics.py
+++ b/core/superduperreload/magics.py
@@ -105,11 +105,8 @@ def __init__(self, *a, **kw):
         if platform.python_implementation().lower() != "cpython":
             raise RuntimeError("CPython required for superduperreload extension")
         flow = kw.pop("flow", None)
-        enable_file_watching = kw.pop("enable_file_watching", True)
         super().__init__(*a, **kw)
-        self._reloader = ModuleReloader(
-            self.shell, flow=flow, enable_file_watching=enable_file_watching
-        )
+        self._reloader = ModuleReloader.instance(self.shell, flow=flow)
         self.loaded_modules = set(sys.modules)
 
     @line_magic
diff --git a/core/superduperreload/patching.py b/core/superduperreload/patching.py
index fd8fab4..ccaca46 100644
--- a/core/superduperreload/patching.py
+++ b/core/superduperreload/patching.py
@@ -7,6 +7,8 @@
 from types import FunctionType, MethodType
 from typing import Callable, Dict, List, Optional, Set, Sized, Tuple, Type, Union
 
+from traitlets.config import SingletonConfigurable
+
 from superduperreload.utils import isinstance2
 
 if sys.maxsize > 2**32:
@@ -82,10 +84,11 @@ class UnpatchableList(list):
     pass
 
 
-class ObjectPatcher:
+class ObjectPatcher(SingletonConfigurable):
     _FIELD_OFFSET_LOOKUP_TABLE_BY_STRUCT_TYPE: Dict[str, Dict[str, int]] = {}
 
-    def __init__(self, patch_referrers: bool) -> None:
+    def __init__(self, patch_referrers: bool, **kwargs) -> None:
+        super().__init__(**kwargs)
         self._patched_obj_ids: Set[int] = set()
         self._remapped_classes: Dict[Type[object], Type[object]] = UnpatchableDict()
         self._patch_rules: List[Tuple[Callable, Callable]] = [
diff --git a/core/superduperreload/superduperreload.py b/core/superduperreload/superduperreload.py
index 379ec68..56741d2 100644
--- a/core/superduperreload/superduperreload.py
+++ b/core/superduperreload/superduperreload.py
@@ -80,12 +80,12 @@
 
 
 class ImportTracer(pyc.BaseTracer):
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         self._reloader: "ModuleReloader" = kwargs.pop("reloader")
         super().__init__(*args, **kwargs)
 
     @pyc.register_raw_handler(pyc.after_import)
-    def after_import(self, *_, module: ModuleType, **__):
+    def after_import(self, *_, module: ModuleType, **__) -> None:
         self._reloader.handle_module_refreshed(module)
 
 
@@ -94,7 +94,6 @@ def __init__(
         self,
         shell: Optional[Union["InteractiveShell", "FakeShell"]] = None,
         flow: Optional["NotebookFlow"] = None,
-        enable_file_watching: bool = True,
     ) -> None:
         super().__init__(patch_referrers=SHOULD_PATCH_REFERRERS)
         # Whether this reloader is enabled
@@ -140,8 +139,22 @@ def __init__(
 
         # Cache module modification times
         self.check(do_reload=False)
-        if self.flow is not None and enable_file_watching:
-            Thread(target=self._watch, daemon=True).start()
+        self._watcher: Optional[Thread] = None
+        self._watcher_running = False
+        if self.flow is not None:
+            self._watcher = Thread(target=self._watch, daemon=True)
+            self._watcher_running = True
+            self._watcher.start()
+
+    @classmethod
+    def clear_instance(cls) -> None:
+        if cls.initialized():
+            reloader: "ModuleReloader" = cls._instance
+            if reloader._watcher_running:
+                reloader._watcher_running = False
+                if reloader._watcher is not None:
+                    reloader._watcher.join()
+        super().clear_instance()
 
     def _report(self, msg: str) -> None:
         if self.verbose:
@@ -303,7 +316,7 @@ def _watch(self, interval: float = 1) -> None:
         assert self.flow is not None
         for m in list(sys.modules.values()):
             self.handle_module_refreshed(m)
-        while True:
+        while self._watcher_running:
             try:
                 with self._reloading_lock:
                     self._poll_module_changes_once()
diff --git a/core/test/test_ipyflow_superduperreload.py b/core/test/test_ipyflow_superduperreload.py
index 7460f31..d9b5034 100644
--- a/core/test/test_ipyflow_superduperreload.py
+++ b/core/test/test_ipyflow_superduperreload.py
@@ -27,6 +27,7 @@
 from ipyflow.tracing.ipyflow_tracer import DataflowTracer
 
 from superduperreload import load_ipython_extension, make_autoreload_magics
+from superduperreload.superduperreload import ModuleReloader
 
 try:
     import numpy
@@ -105,13 +106,12 @@ def setUp(self):
         self.test_dir = tempfile.mkdtemp()
         self.old_sys_path = list(sys.path)
         sys.path.insert(0, self.test_dir)
+        ModuleReloader.clear_instance()
         DataflowTracer.clear_instance()
         NotebookFlow.clear_instance()
         IPyflowInteractiveShell.clear_instance()
         self.shell = IPyflowInteractiveShell.instance()
-        self.auto_magics = make_autoreload_magics(
-            self.shell, enable_file_watching=False
-        )
+        self.auto_magics = make_autoreload_magics(self.shell)
         load_ipython_extension(self.shell, magics=self.auto_magics)
 
     def tearDown(self):