diff --git a/IPython/core/history.py b/IPython/core/history.py
index da10813..c9b8435 100644
--- a/IPython/core/history.py
+++ b/IPython/core/history.py
@@ -775,6 +775,7 @@ class HistorySavingThread(threading.Thread):
             while True:
                 self.history_manager.save_flag.wait()
                 if self.stop_now:
+                    self.db.close()
                     return
                 self.history_manager.save_flag.clear()
                 self.history_manager.writeout_cache(self.db)
diff --git a/IPython/core/tests/test_history.py b/IPython/core/tests/test_history.py
index 1ec2852..c08156b 100644
--- a/IPython/core/tests/test_history.py
+++ b/IPython/core/tests/test_history.py
@@ -136,6 +136,8 @@ def test_history():
         finally:
             # Ensure saving thread is shut down before we try to clean up the files
             ip.history_manager.save_thread.stop()
+            # Forcibly close database rather than relying on garbage collection
+            ip.history_manager.db.close()
             # Restore history manager
             ip.history_manager = hist_manager_ori