diff --git a/labelme/app.py b/labelme/app.py
index 5b5c6e94d..3ca529f32 100644
--- a/labelme/app.py
+++ b/labelme/app.py
@@ -8,6 +8,7 @@
 import webbrowser
 
 import imgviz
+import natsort
 from qtpy import QtCore
 from qtpy.QtCore import Qt
 from qtpy import QtGui
@@ -2075,5 +2076,5 @@ def scanAllImages(self, folderPath):
                 if file.lower().endswith(tuple(extensions)):
                     relativePath = osp.join(root, file)
                     images.append(relativePath)
-        images.sort(key=lambda x: x.lower())
+        images = natsort.os_sorted(images)
         return images
diff --git a/setup.py b/setup.py
index ecacbb3a4..21bf73d81 100644
--- a/setup.py
+++ b/setup.py
@@ -31,6 +31,7 @@ def get_install_requires():
     install_requires = [
         "imgviz>=0.11",
         "matplotlib<3.3",  # for PyInstaller
+        "natsort>=7.1.0",
         "numpy",
         "Pillow>=2.8",
         "PyYAML",