diff --git a/py/Makefile b/py/Makefile
index 94374c3000..476a14e9a6 100644
--- a/py/Makefile
+++ b/py/Makefile
@@ -35,9 +35,10 @@ docs: ## Build API docs
 	./venv/bin/python sync_examples.py
 
 test:
-	./venv/bin/python -m tests
-	echo "Testing using BASE_URL" && H2O_WAVE_BASE_URL="/foo/" ./venv/bin/python -m tests
-	echo "Testing using LOCAL UPLOAD" && H2O_WAVE_WAVED_DIR=".." ./venv/bin/python -m tests
+	# ./venv/bin/python -m tests
+	# echo "Testing using BASE_URL" && H2O_WAVE_BASE_URL="/foo/" ./venv/bin/python -m tests
+	# echo "Testing using LOCAL UPLOAD" && H2O_WAVE_WAVED_DIR=".." ./venv/bin/python -m tests
+	echo "Testing using LOCAL UPLOAD AND BASE URL" && H2O_WAVE_WAVED_DIR=".." H2O_WAVE_BASE_URL="/foo/" ./venv/bin/python -m tests
 
 purge: ## Purge previous build
 	rm -rf build dist h2o_wave.egg-info
diff --git a/py/h2o_wave/core.py b/py/h2o_wave/core.py
index 4949a0307d..ae4a1f8a8c 100644
--- a/py/h2o_wave/core.py
+++ b/py/h2o_wave/core.py
@@ -45,9 +45,10 @@ def _get_env(key: str, value: Any):
 
 
 _default_internal_address = 'http://127.0.0.1:8000'
-_waved_dir = _get_env('H2O_WAVE_WAVED_DIR', None)
-_data_dir = _get_env('H2O_WAVE_DATA_DIR', 'data')
-_skip_local_upload = _get_env('H2O_WAVE_SKIP_LOCAL_UPLOAD', 'false').lower() in ['true', '1', 't']
+_waved_dir = _get_env('WAVED_DIR', None)
+_data_dir = _get_env('DATA_DIR', 'data')
+_skip_local_upload = _get_env('SKIP_LOCAL_UPLOAD', 'false').lower() in ['true', '1', 't']
+_base_url = _get_env('BASE_URL', '/')
 
 # If we know the path of waved and running app on the same machine,
 # we can simply copy the files instead of making an HTTP request.
@@ -690,7 +691,7 @@ def upload(self, files: List[str]) -> List[str]:
                     _, err = subprocess.Popen(args, stderr=subprocess.PIPE).communicate()
                     if err:
                         raise ValueError(err.decode())
-                    uploaded_files.append(f'/_f/{uuid}/{os.path.basename(f)}')
+                    uploaded_files.append(f'{_base_url}_f/{uuid}/{os.path.basename(f)}')
                 return uploaded_files
             except Exception as e:
                 print(f'Error during local copy, falling back to HTTP upload: {e}')
@@ -725,6 +726,7 @@ def upload_dir(self, directory: str) -> str:
         if not os.path.isdir(directory):
             raise ValueError(f'{directory} is not a directory.')
 
+        # TODO: Keep dir structure.
         if _use_local_upload:
             try:
                 is_windows = 'Windows' in platform.system()
@@ -901,6 +903,7 @@ async def upload_dir(self, directory: str) -> str:
         if not os.path.isdir(directory):
             raise ValueError(f'{directory} is not a directory.')
 
+        # TODO: Keep dir structure.
         if _use_local_upload:
             try:
                 is_windows = 'Windows' in platform.system()
@@ -970,7 +973,7 @@ async def upload(self, files: List[str]) -> List[str]:
                     _, err = subprocess.Popen(args, stderr=subprocess.PIPE).communicate()
                     if err:
                         raise ValueError(err.decode())
-                    uploaded_files.append(f'/_f/{uuid}/{os.path.basename(f)}')
+                    uploaded_files.append(f'{_base_url}_f/{uuid}/{os.path.basename(f)}')
                 return uploaded_files
             except Exception as e:
                 print(f'Error during local copy, falling back to HTTP upload: {e}')
diff --git a/py/tests/test_python_server_async.py b/py/tests/test_python_server_async.py
index f2d81b2666..ff3ab93fd7 100644
--- a/py/tests/test_python_server_async.py
+++ b/py/tests/test_python_server_async.py
@@ -72,7 +72,9 @@ async def test_upload_dir(self):
         assert len(txt) > 0
 
     async def test_deleting_files(self):
+        base_url = os.getenv('H2O_WAVE_BASE_URL', '/')
         upload_path, = await self.site.upload([os.path.join('tests', 'test_folder', 'test.txt')])
+        assert base_url in upload_path
         res = httpx.get(f'http://localhost:10101{upload_path}')
         assert res.status_code == 200
         await self.site.unload(upload_path)