diff --git a/trytond/trytond/backend/sqlite/database.py b/trytond/trytond/backend/sqlite/database.py
index eafd286785..3f08d66e9d 100644
--- a/trytond/trytond/backend/sqlite/database.py
+++ b/trytond/trytond/backend/sqlite/database.py
@@ -441,14 +441,25 @@ class Database(DatabaseInterface):
         return self._conn
 
     def put_connection(self, connection=None, close=False):
-        pass
+        assert connection == self._conn or self._conn is None
+        if self.name == ':memory:':
+            if (self._local.memory_database._conn is None
+                    and connection and close):
+                connection.close()
+                self._conn = None
+        elif close:
+            connection.close()
+            self._conn = None
 
     def close(self):
         if self.name == ':memory:':
-            return
-        if self._conn is None:
-            return
-        self._conn = None
+            if (self._local.memory_database._conn is None
+                    and self._conn):
+                self._conn.close()
+                self._conn = None
+        elif self._conn:
+            self._conn.close()
+            self._conn = None
 
     @classmethod
     def create(cls, connection, database_name):