diff --git a/src/scorep_jupyter/kernel_messages.py b/src/scorep_jupyter/kernel_messages.py
index de8b110..bd5a3fa 100644
--- a/src/scorep_jupyter/kernel_messages.py
+++ b/src/scorep_jupyter/kernel_messages.py
@@ -1,3 +1,4 @@
+import os
 from enum import Enum, auto
 
 from .logging_config import LOGGING
diff --git a/src/scorep_jupyter/userpersistence.py b/src/scorep_jupyter/userpersistence.py
index 9ed5948..520b081 100644
--- a/src/scorep_jupyter/userpersistence.py
+++ b/src/scorep_jupyter/userpersistence.py
@@ -501,7 +501,6 @@ def stop(self, done_message="Done."):
 
 
 def create_busy_spinner(lock=None, stop_event=None, is_multicell_final=False):
-
     is_enabled = str(
         os.getenv("SCOREP_JUPYTER_DISABLE_PROCESSING_ANIMATIONS")
     ).lower() not in ["true", "1", "t"]