diff --git a/process_manager.py b/process_manager.py
index ea4c928..09d3bba 100644
--- a/process_manager.py
+++ b/process_manager.py
@@ -104,10 +104,11 @@ class ProcessManager:
             return
         self.state = ProcessManagerState.IDLE
         self.task.cancel()
-        try:
-            os.kill(self.pid, signal.SIGINT)
-        except Exception as err:
-            logging.warning(f"kill failed: {err}")
+        if self.pid:
+            try:
+                os.kill(self.pid, signal.SIGINT)
+            except Exception as err:
+                logging.warning(f"kill failed: {err}")
 
         self.task.cancel()
         self.pid = 0