diff --git a/labscript_utils/device_registry/_device_registry.py b/labscript_utils/device_registry/_device_registry.py
index 0c64cb2..e5a122a 100644
--- a/labscript_utils/device_registry/_device_registry.py
+++ b/labscript_utils/device_registry/_device_registry.py
@@ -1,3 +1,4 @@
+import importlib.machinery
 import os
 import importlib
 import warnings
@@ -6,11 +7,6 @@
 from labscript_utils import dedent
 from labscript_utils.labconfig import LabConfig
 
-# deal with removal of imp from python 3.12
-try:
-    import _imp as imp
-except ImportError:
-    import imp
 
 """This file contains the machinery for registering and looking up what BLACS tab and
 runviewer parser classes belong to a particular labscript device. "labscript device"
@@ -253,20 +249,19 @@ def register_classes(labscript_device_name, BLACS_tab=None, runviewer_parser=Non
 
 def populate_registry():
     """Walk the labscript_devices folder looking for files called register_classes.py,
-    and run them (i.e. import them). These files are expected to make calls to
+    and run them. These files are expected to make calls to
     register_classes() to inform us of what BLACS tabs and runviewer classes correspond
     to their labscript device classes."""
-    # We import the register_classes modules as a direct submodule of labscript_devices.
-    # But they cannot all have the same name, so we import them as
-    # labscript_devices._register_classes_script_<num> with increasing number.
-    module_num = 0
+    # We execute the register_classes modules as a direct submodule of labscript_devices.
     for devices_dir in LABSCRIPT_DEVICES_DIRS:
         for folder, _, filenames in os.walk(devices_dir):
             if 'register_classes.py' in filenames:
                 # The module name is the path to the file, relative to the labscript suite
                 # install directory:
-                # Open the file using the import machinery, and import it as module_name.
-                fp, pathname, desc = imp.find_module('register_classes', [folder])
-                module_name = 'labscript_devices._register_classes_%d' % module_num
-                _ = imp.load_module(module_name, fp, pathname, desc)
-                module_num += 1
+                # Open the file using the import machinery, and run it
+                spec = importlib.machinery.PathFinder.find_spec('register_classes', [folder])
+                mod = importlib.util.module_from_spec(spec)
+                spec.loader.exec_module(mod)
+                # fully importing module would require adding to sys.modules
+                # and each import would need to have unique names
+                # but we just need to run the registering code, not actually import the module
diff --git a/labscript_utils/modulewatcher.py b/labscript_utils/modulewatcher.py
index d9029dd..ec1cdb1 100644
--- a/labscript_utils/modulewatcher.py
+++ b/labscript_utils/modulewatcher.py
@@ -17,12 +17,6 @@
 import site
 import sysconfig
 
-# deal with removal of imp from python 3.12
-try:
-    import _imp as imp
-except ImportError:
-    import imp
-
 
 # Directories in which the standard library and installed packages may be located.
 # Modules in these locations will be whitelisted:
@@ -63,16 +57,8 @@ def mainloop(self):
         while True:
             time.sleep(1)
             with self.lock:
-                # Acquire the import lock so that we don't unload modules whilst an
-                # import is in progess:
-                imp.acquire_lock()
-                try:
-                    if self.check():
-                        self.unload()
-                finally:
-                    # We're done mucking around with the cached modules, normal imports
-                    # in other threads may resume:
-                    imp.release_lock()
+                if self.check():
+                    self.unload()
 
     def check(self):
         unload_required = False
@@ -138,3 +124,32 @@ def unload(self):
         # code holds references to sys.meta_path, and to preserve order, since order
         # is relevant.
         sys.meta_path[:] = self.meta_whitelist
+
+if __name__ == "__main__":
+
+    from pathlib import Path
+    import time
+
+    dict1 = {'t': 5, 'val': 10}
+    dict2 = {'t': 5, 'val': 11}
+
+    print('ModuleWatcher instatiated in debug mode')
+    module_watcher = ModuleWatcher(debug=True)
+
+    # import a local module
+    import labscript_utils.dict_diff
+    print('imported labscript_utils.dict_diff')
+    print(labscript_utils.dict_diff.dict_diff(dict1, dict2))
+    print('used dict_diff function, waiting 2 seconds for module watcher to update')
+    time.sleep(2)
+
+    # now pretend it has been updated
+    ex_mod = Path('dict_diff.py')
+    ex_mod.touch()
+    print('dict_diff module touched, waiting 2 seconds for ModuleWatcher to notice')
+    time.sleep(2)
+
+    print(labscript_utils.dict_diff.dict_diff(dict1, dict2))
+    print('Used dict_diff again, waiting 2 seconds for ModuleWatcher to not do anything')
+    time.sleep(2)
+    
\ No newline at end of file

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