diff --git a/python/eups/app.py b/python/eups/app.py
index ee4e59fd..cf844e7c 100644
--- a/python/eups/app.py
+++ b/python/eups/app.py
@@ -339,7 +339,7 @@ def printUses(outstrm, productName, versionName=None, eupsenv=None,
         usesInfo = eupsenv.uses()
         if pickleFile:
             with utils.AtomicFile(pickleFile, "wb") as fd:
-                pickle.dump(usesInfo, fd, protocol=2)
+                pickle.dump(usesInfo, fd, protocol=4)
 
     userList = eupsenv.uses(productName, versionName, depth, usesInfo=usesInfo)
 
diff --git a/python/eups/stack/ProductStack.py b/python/eups/stack/ProductStack.py
index ceae9ae3..af0e189d 100644
--- a/python/eups/stack/ProductStack.py
+++ b/python/eups/stack/ProductStack.py
@@ -306,7 +306,7 @@ def persist(self, flavor, file=None):
         flavorData = self.lookup[flavor]
 
         with utils.AtomicFile(file, "wb") as fd:
-            pickle.dump(flavorData, fd, protocol=2)
+            pickle.dump(flavorData, fd, protocol=4)
         # This could fail if another process deleted the file immediately.
         with contextlib.suppress(FileNotFoundError):
             self.modtimes[file] = os.stat(file).st_mtime