diff --git a/ipykernel/kernelbase.py b/ipykernel/kernelbase.py
index 24c081d49..7c37b3cc7 100644
--- a/ipykernel/kernelbase.py
+++ b/ipykernel/kernelbase.py
@@ -76,7 +76,7 @@ class Kernel(SingletonConfigurable):
     # attribute to override with a GUI
     eventloop = Any(None)
 
-    processes: dict[str, psutil.Process] = {}
+    processes: t.Dict[str, psutil.Process] = {}
 
     @observe("eventloop")
     def _update_eventloop(self, change):