diff --git a/.github/workflows/test-with-pip.yml b/.github/workflows/test-with-pip.yml
index 35004508..38ceb699 100644
--- a/.github/workflows/test-with-pip.yml
+++ b/.github/workflows/test-with-pip.yml
@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ['3.7', '3.8', '3.9', '3.10']
+        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
 
     runs-on: ${{ matrix.os }}
 
diff --git a/apptools/persistence/state_pickler.py b/apptools/persistence/state_pickler.py
index 079dcd63..6857e7f5 100644
--- a/apptools/persistence/state_pickler.py
+++ b/apptools/persistence/state_pickler.py
@@ -393,11 +393,14 @@ def _do_instance(self, value):
             args = value.__getinitargs__()
 
         # Get the object state.
+        state = None
         if hasattr(value, "__get_pure_state__"):
             state = value.__get_pure_state__()
         elif hasattr(value, "__getstate__"):
+            # Note that __getstate__() may return None in Python >= 3.11
             state = value.__getstate__()
-        else:
+
+        if state is None:
             state = value.__dict__
 
         state.pop("__traits_version__", None)
diff --git a/docs/releases/upcoming/328.bugfix.rst b/docs/releases/upcoming/328.bugfix.rst
new file mode 100644
index 00000000..f55976de
--- /dev/null
+++ b/docs/releases/upcoming/328.bugfix.rst
@@ -0,0 +1 @@
+Fix StatePickler for Python 3.11. (#328)
\ No newline at end of file