diff --git a/artiq/master/databases.py b/artiq/master/databases.py
index d889933d7..5cb866dd7 100644
--- a/artiq/master/databases.py
+++ b/artiq/master/databases.py
@@ -1,4 +1,5 @@
 import asyncio
+import pathlib
 
 import lmdb
 
@@ -21,7 +22,7 @@ def device_db_from_file(filename):
 
 class DeviceDB:
     def __init__(self, backing_file):
-        self.backing_file = backing_file
+        self.backing_file = pathlib.Path(backing_file).resolve()
         self.data = Notifier(device_db_from_file(self.backing_file))
 
     def scan(self):
diff --git a/artiq/master/worker_db.py b/artiq/master/worker_db.py
index af316e4cf..375a78ab9 100644
--- a/artiq/master/worker_db.py
+++ b/artiq/master/worker_db.py
@@ -3,7 +3,7 @@
 These artefacts are intended for out-of-process use (i.e. from workers or the
 standalone command line tools).
 """
-
+import sys
 from operator import setitem
 import importlib
 import logging
@@ -22,9 +22,12 @@ class DummyDevice:
 def _create_device(desc, device_mgr, argument_overrides):
     ty = desc["type"]
     if ty == "local":
+        path = str(device_mgr.ddb.backing_file.parent)
+        sys.path.insert(0, path)
         module = importlib.import_module(desc["module"])
         device_class = getattr(module, desc["class"])
         arguments = desc.get("arguments", {}) | argument_overrides
+        sys.path.pop(0)
         return device_class(device_mgr, **arguments)
     elif ty == "controller":
         if desc.get("best_effort", False):
diff --git a/artiq/tools.py b/artiq/tools.py
index e11afe2bb..a983cdae1 100644
--- a/artiq/tools.py
+++ b/artiq/tools.py
@@ -122,7 +122,7 @@ def short_format(v, metadata={}):
 
 
 def file_import(filename, prefix="file_import_"):
-    filename = pathlib.Path(filename)
+    filename = pathlib.Path(filename) if not isinstance(filename, pathlib.Path) else filename
     modname = prefix + filename.stem
 
     path = str(filename.resolve().parent)