diff --git a/sqlalchemy_utils/functions/database.py b/sqlalchemy_utils/functions/database.py
index 71f746f..ff847a5 100644
--- a/sqlalchemy_utils/functions/database.py
+++ b/sqlalchemy_utils/functions/database.py
@@ -399,7 +399,7 @@ def drop_database(url):
         engine.raw_connection().set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)
 
         # Disconnect all users from the database we are dropping.
-        version = map(int, engine.execute('SHOW server_version;').first()[0].split('.'))
+        version = list(map(int, engine.execute('SHOW server_version;').first()[0].split('.')))
         pid_column = 'pid' if (version[0] >= 9 and version[1] >= 2) else 'procpid'
         text = '''
         SELECT pg_terminate_backend(pg_stat_activity.%(pid_column)s)