diff --git a/maubot/handlers/command.py b/maubot/handlers/command.py
index 4d0058f..bee5509 100644
--- a/maubot/handlers/command.py
+++ b/maubot/handlers/command.py
@@ -26,8 +26,9 @@ from mautrix.types import MessageType, EventType
 from ..matrix import MaubotMessageEvent
 from . import event
 
-PrefixType = Optional[Union[str, Callable[[], str]]]
-AliasesType = Union[List[str], Tuple[str, ...], Set[str], Callable[[str], bool]]
+PrefixType = Optional[Union[str, Callable[[], str], Callable[[Any], str]]]
+AliasesType = Union[List[str], Tuple[str, ...], Set[str], Callable[[str], bool],
+                    Callable[[Any, str], bool]]
 CommandHandlerFunc = NewType("CommandHandlerFunc",
                              Callable[[MaubotMessageEvent, Any], Awaitable[Any]])
 CommandHandlerDecorator = NewType("CommandHandlerDecorator",
diff --git a/maubot/plugin_base.py b/maubot/plugin_base.py
index b2608c8..034ccef 100644
--- a/maubot/plugin_base.py
+++ b/maubot/plugin_base.py
@@ -30,6 +30,7 @@ if TYPE_CHECKING:
 
 class Plugin(ABC):
     client: 'MaubotMatrixClient'
+    http: ClientSession
     id: str
     log: Logger
     loop: AbstractEventLoop