diff --git a/tests/conftest.py b/tests/conftest.py
index 1a0a768..b917654 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -19,6 +19,10 @@ class TempDirs(typing.NamedTuple):
     toy_data_path: Path
 
 
+def path_str(dir_path: Path, filename: str) -> str:
+    return str(dir_path.joinpath(filename))
+
+
 def pytest_addoption(parser):
     """Sets up optional argument to keep temporary testing directory."""
     parser.addoption(
diff --git a/tests/unit/test_run_stitchee.py b/tests/unit/test_run_stitchee.py
index b5377c2..11e58d1 100644
--- a/tests/unit/test_run_stitchee.py
+++ b/tests/unit/test_run_stitchee.py
@@ -7,9 +7,7 @@
 import concatenator
 from concatenator.run_stitchee import parse_args
 
-
-def path_str(dir_path: Path, filename: str) -> str:
-    return str(dir_path.joinpath(filename))
+from ..conftest import path_str
 
 
 def test_parser():