diff --git a/nbdev/test.py b/nbdev/test.py
index d819e69a8..4a04e2ed3 100644
--- a/nbdev/test.py
+++ b/nbdev/test.py
@@ -20,6 +20,7 @@
 from .doclinks import *
 from .process import NBProcessor, nb_lang
 from .frontmatter import nb_frontmatter
+from .processors import _default_exp
 
 from fastcore.nbio import *
 from execnb.shell import *
@@ -58,6 +59,8 @@ def _no_eval(cell):
         start = time.time()
         if profile is None: profile = bool(get_config(fn.parent).exec_profile)
         k = CaptureShell(fn, profile=profile)
+        exp = _default_exp(nb)
+        if exp and is_nbdev(fn.parent): k.user_ns['__file__'] = str(get_config(fn.parent).lib_path/(exp.replace('.','/') + '.py'))
         if do_print: print(f'Starting {fn}')
         try:
             with working_directory(fn.parent):
@@ -73,7 +76,6 @@ def _no_eval(cell):
         if prev_test is None: os.environ.pop('IN_TEST', None)
         else: os.environ['IN_TEST'] = prev_test
 
-
 # %% ../nbs/api/12_test.ipynb #d8bf1f1b-935d-4b69-ba96-827c5d7213f0
 def _keep_file(
     p:Path, # filename for which to check for `indicator_fname`
diff --git a/nbs/api/12_test.ipynb b/nbs/api/12_test.ipynb
index f1b025906..5147e397d 100644
--- a/nbs/api/12_test.ipynb
+++ b/nbs/api/12_test.ipynb
@@ -40,6 +40,7 @@
     "from nbdev.doclinks import *\n",
     "from nbdev.process import NBProcessor, nb_lang\n",
     "from nbdev.frontmatter import nb_frontmatter\n",
+    "from nbdev.processors import _default_exp\n",
     "\n",
     "from fastcore.nbio import *\n",
     "from execnb.shell import *"
@@ -86,6 +87,8 @@
     "        start = time.time()\n",
     "        if profile is None: profile = bool(get_config(fn.parent).exec_profile)\n",
     "        k = CaptureShell(fn, profile=profile)\n",
+    "        exp = _default_exp(nb)\n",
+    "        if exp and is_nbdev(fn.parent): k.user_ns['__file__'] = str(get_config(fn.parent).lib_path/(exp.replace('.','/') + '.py'))\n",
     "        if do_print: print(f'Starting {fn}')\n",
     "        try:\n",
     "            with working_directory(fn.parent):\n",
@@ -99,7 +102,7 @@
     "        return res,time.time()-start\n",
     "    finally:\n",
     "        if prev_test is None: os.environ.pop('IN_TEST', None)\n",
-    "        else: os.environ['IN_TEST'] = prev_test\n"
+    "        else: os.environ['IN_TEST'] = prev_test"
    ]
   },
   {
@@ -142,6 +145,26 @@
     "assert not success"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "239fbed8",
+   "metadata": {},
+   "source": [
+    "If a notebook declares a `default_exp`, `__file__` is set to the path of the module it exports to, so path-dependent code (e.g. `Path(__file__).parent`) behaves the same under test as in the exported module. An explicit `__file__ =` in a cell overrides this:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "f07e8a6e",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "_nb = Path('../../tests/file_var.ipynb')\n",
+    "success,duration = test_nb(_nb)\n",
+    "assert success"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
diff --git a/tests/file_var.ipynb b/tests/file_var.ipynb
new file mode 100644
index 000000000..190d1c7ae
--- /dev/null
+++ b/tests/file_var.ipynb
@@ -0,0 +1,50 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test `__file__` is set for exported notebooks"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| default_exp file_var"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from pathlib import Path\n",
+    "p = Path(__file__)\n",
+    "assert p.name == 'file_var.py' and p.parent.name == 'nbdev'"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "__file__ = 'overridden'\n",
+    "assert __file__ == 'overridden'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}