diff --git a/cspell.json b/cspell.json
index c271670..1b5f95d 100644
--- a/cspell.json
+++ b/cspell.json
@@ -118,6 +118,7 @@
 		"psutil",
 		"pybabel",
 		"pycache",
+		"pyfakefs",
 		"pyfiglet",
 		"Pylance",
 		"pyobjc",
diff --git a/requirements.txt b/requirements.txt
index d0fad9c..6af68b5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -14,3 +14,4 @@ types-Pillow==10.0.0.1 # for development
 types-psutil==5.9.5.15 # for development
 pytest==7.4.1 # for development
 pytest-textual-snapshot==0.4.0 # for development
+pyfakefs==5.2.4 # for development
diff --git a/src/textual_paint/enhanced_directory_tree.py b/src/textual_paint/enhanced_directory_tree.py
index b9dbaf8..0e7689a 100644
--- a/src/textual_paint/enhanced_directory_tree.py
+++ b/src/textual_paint/enhanced_directory_tree.py
@@ -163,7 +163,11 @@ class EnhancedDirectoryTree(DirectoryTree):
 
         if callback is None:
             callback = lambda: None
-        self._expand_matching_child(self.root, target_path.parts[1:], callback)
+        
+        remaining_parts = target_path.parts[1:]
+        # True unless target_path is the root (edge case which occurs when testing with pyfakefs).
+        if len(remaining_parts) > 1:
+            self._expand_matching_child(self.root, remaining_parts, callback)
 
     def render_label(
         self, node: TreeNode[DirEntry], base_style: Style, style: Style
diff --git a/tests/test_snapshots.py b/tests/test_snapshots.py
index 33f808c..8b4a957 100644
--- a/tests/test_snapshots.py
+++ b/tests/test_snapshots.py
@@ -1,12 +1,17 @@
 from pathlib import Path, PurePath
-from typing import TYPE_CHECKING, Awaitable, Callable, Iterable, Protocol
+from typing import (TYPE_CHECKING, Awaitable, Callable, Generator, Iterable,
+                    Protocol)
 
+import pyfakefs
 import pytest
+from pyfakefs.fake_file import FakeDirectory
+from pyfakefs.fake_filesystem import FakeFilesystem
 from textual.geometry import Offset
 from textual.pilot import Pilot
 from textual.widgets import Input
 
 from tests.pilot_helpers import click_by_attr, click_by_index, drag
+from textual_paint.figlet_font_writer import FIGletFontWriter
 
 if TYPE_CHECKING:
     # When tests are run, paint.py is re-evaluated,
@@ -58,6 +63,38 @@ def each_theme(request: pytest.FixtureRequest):
     args.theme = "light"
     args.ascii_only = False
 
+APPS_DIR_ABSOLUTE = (Path(__file__).parent / APPS_DIR).resolve()
+TESTS_DIR_ABSOLUTE = Path(__file__).parent.resolve()
+
+@pytest.fixture
+def my_fs(fs: FakeFilesystem) -> Generator[FakeFilesystem, None, None]:
+    print("adding real directory", APPS_DIR_ABSOLUTE)
+    fs.add_real_directory(APPS_DIR_ABSOLUTE)
+    
+    # Without this, pytest-textual-snapshot will show "No history for this test"
+    print("adding real directory", TESTS_DIR_ABSOLUTE)
+    fs.add_real_directory(TESTS_DIR_ABSOLUTE)
+
+    # TODO: use proper mocking or figure out how to get FigletFont to find the real font files.
+    # This folder doesn't actually exist on my system, so it's not getting them from there.
+    # from pyfiglet import SHARED_DIRECTORY
+    # fs.add_real_directory(SHARED_DIRECTORY)
+
+    # Don't fail trying to load the default font "standard", we don't need it!
+    # `pkg_resources` doesn't seem to work with pyfakefs.
+    from pyfiglet import FigletFont
+    def preloadFont(self: FigletFont, font: str):
+        dumb_font = FIGletFontWriter(commentLines=["Stupid font for testing"])
+        for ordinal in dumb_font.charOrder:
+            dumb_font.figChars[ordinal] = "fallback font for testing"
+        return dumb_font.createFigFileData()
+    FigletFont.preloadFont = preloadFont
+  
+    # Add an extra file to show how a file looks in the EnhancedDirectoryTree widget.
+    fs.create_file("/pyfakefs_added_file.txt", contents="pyfakefs ate ur FS")
+
+    yield fs
+
 
 def test_paint_app(snap_compare: SnapCompareType, each_theme: None):
     assert snap_compare(PAINT, terminal_size=LARGER)
@@ -71,10 +108,10 @@ def test_paint_flip_rotate_dialog(snap_compare: SnapCompareType, each_theme: Non
 def test_paint_image_attributes_dialog(snap_compare: SnapCompareType, each_theme: None):
     assert snap_compare(PAINT, press=["ctrl+e"])
 
-def test_paint_open_dialog(snap_compare: SnapCompareType, each_theme: None):
+def test_paint_open_dialog(snap_compare: SnapCompareType, each_theme: None, my_fs: None):
     assert snap_compare(PAINT, press=["ctrl+o"], terminal_size=LARGER)
 
-def test_paint_save_dialog(snap_compare: SnapCompareType, each_theme: None):
+def test_paint_save_dialog(snap_compare: SnapCompareType, each_theme: None, my_fs: None):
     assert snap_compare(PAINT, press=["ctrl+s"], terminal_size=LARGER)
 
 def test_paint_help_dialog(snap_compare: SnapCompareType, each_theme: None):