diff --git a/setup.py b/setup.py
index 8af3d63..d16e5d8 100644
--- a/setup.py
+++ b/setup.py
@@ -20,7 +20,7 @@
     python_requires=">=3.7",
     install_requires=[
         'msal>=1.29,<2',  # Use TokenCache.search() from MSAL Python 1.29+
-        'portalocker<3,>=1.4',
+        'portalocker<4,>=1.4',
 
         ## We choose to NOT define a hard dependency on this.
         # "pygobject>=3,<4;platform_system=='Linux'",