diff --git a/src/dispatching/dispatcher.rs b/src/dispatching/dispatcher.rs
index 0d094fc0..97c63f1b 100644
--- a/src/dispatching/dispatcher.rs
+++ b/src/dispatching/dispatcher.rs
@@ -16,52 +16,55 @@ use futures::StreamExt;
 use std::fmt::Debug;
 
 pub struct BasicHandlerCtx<'a, Upd> {
-    bot: &'a Bot,
-    update: Upd,
+    pub bot: &'a Bot,
+    pub update: Upd,
 }
 
 pub struct Dispatcher<'a, Session1, Session2, H1, H2, HandlerE> {
     bot: &'a Bot,
 
-    handlers_error_handler: Box<dyn Handler<HandlerE, ()>>,
+    handlers_error_handler: Box<dyn Handler<HandlerE, ()> + 'a>,
 
     private_message_dp: Option<SessionDispatcher<'a, Session1, H1>>,
     private_edited_message_dp: Option<SessionDispatcher<'a, Session2, H2>>,
 
-    message_handler: Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()>>>,
+    message_handler:
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()> + 'a>>,
     edited_message_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()>>>,
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()> + 'a>>,
     channel_post_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()>>>,
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()> + 'a>>,
     edited_channel_post_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()>>>,
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, Message>, ()> + 'a>>,
     inline_query_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, InlineQuery>, ()>>>,
-    chosen_inline_result_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, ChosenInlineResult>, ()>>>,
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, InlineQuery>, ()> + 'a>>,
+    chosen_inline_result_handler: Option<
+        Box<dyn Handler<BasicHandlerCtx<'a, ChosenInlineResult>, ()> + 'a>,
+    >,
     callback_query_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, CallbackQuery>, ()>>>,
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, CallbackQuery>, ()> + 'a>>,
     shipping_query_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, ShippingQuery>, ()>>>,
-    pre_checkout_query_handler:
-        Option<Box<dyn Handler<BasicHandlerCtx<'a, PreCheckoutQuery>, ()>>>,
-    poll_handler: Option<Box<dyn Handler<BasicHandlerCtx<'a, Poll>, ()>>>,
+        Option<Box<dyn Handler<BasicHandlerCtx<'a, ShippingQuery>, ()> + 'a>>,
+    pre_checkout_query_handler: Option<
+        Box<dyn Handler<BasicHandlerCtx<'a, PreCheckoutQuery>, ()> + 'a>,
+    >,
+    poll_handler: Option<Box<dyn Handler<BasicHandlerCtx<'a, Poll>, ()> + 'a>>,
 }
 
 impl<'a, Session1, Session2, H1, H2, HandlerE>
     Dispatcher<'a, Session1, Session2, H1, H2, HandlerE>
 where
-    Session1: Default,
-    Session2: Default,
+    Session1: Default + 'a,
+    Session2: Default + 'a,
     H1: Handler<
-        SessionHandlerCtx<'a, Message, Session1>,
-        SessionState<Session1>,
-    >,
+            SessionHandlerCtx<'a, Message, Session1>,
+            SessionState<Session1>,
+        > + 'a,
     H2: Handler<
-        SessionHandlerCtx<'a, Message, Session2>,
-        SessionState<Session2>,
-    >,
-    HandlerE: Debug,
+            SessionHandlerCtx<'a, Message, Session2>,
+            SessionState<Session2>,
+        > + 'a,
+    HandlerE: Debug + 'a,
 {
     pub fn new(bot: &'a Bot) -> Self {
         Self {
@@ -82,6 +85,14 @@ where
         }
     }
 
+    pub fn handlers_error_handler<T>(mut self, val: T) -> Self
+    where
+        T: Handler<HandlerE, ()> + 'a,
+    {
+        self.handlers_error_handler = Box::new(val);
+        self
+    }
+
     pub fn private_message_dp(
         mut self,
         dp: SessionDispatcher<'a, Session1, H1>,
@@ -90,37 +101,115 @@ where
         self
     }
 
-    async fn dispatch(&'a mut self)
+    pub fn private_edited_message_dp(
+        mut self,
+        dp: SessionDispatcher<'a, Session2, H2>,
+    ) -> Self {
+        self.private_edited_message_dp = Some(dp);
+        self
+    }
+
+    pub fn message_handler<H>(mut self, h: H) -> Self
     where
-        Session1: 'a,
-        Session2: 'a,
-        H1: 'a,
-        H2: 'a,
-        HandlerE: 'a,
+        H: Handler<BasicHandlerCtx<'a, Message>, ()> + 'a,
     {
+        self.message_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn edited_message_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, Message>, ()> + 'a,
+    {
+        self.edited_message_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn channel_post_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, Message>, ()> + 'a,
+    {
+        self.channel_post_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn edited_channel_post_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, Message>, ()> + 'a,
+    {
+        self.edited_channel_post_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn inline_query_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, InlineQuery>, ()> + 'a,
+    {
+        self.inline_query_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn chosen_inline_result_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, ChosenInlineResult>, ()> + 'a,
+    {
+        self.chosen_inline_result_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn callback_query_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, CallbackQuery>, ()> + 'a,
+    {
+        self.callback_query_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn shipping_query_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, ShippingQuery>, ()> + 'a,
+    {
+        self.shipping_query_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn pre_checkout_query_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, PreCheckoutQuery>, ()> + 'a,
+    {
+        self.pre_checkout_query_handler = Some(Box::new(h));
+        self
+    }
+
+    pub fn poll_handler<H>(mut self, h: H) -> Self
+    where
+        H: Handler<BasicHandlerCtx<'a, Poll>, ()> + 'a,
+    {
+        self.poll_handler = Some(Box::new(h));
+        self
+    }
+
+    pub async fn dispatch(&'a mut self) {
         self.dispatch_with_listener(
             update_listeners::polling_default(self.bot),
-            error_handlers::Log,
+            &error_handlers::Log,
         )
         .await;
     }
 
-    async fn dispatch_with_listener<UListener, ListenerE, Eh>(
-        &'a mut self,
+    pub async fn dispatch_with_listener<UListener, ListenerE, Eh>(
+        &'a self,
         update_listener: UListener,
-        update_listener_error_handler: Eh,
+        update_listener_error_handler: &'a Eh,
     ) where
         UListener: UpdateListener<ListenerE> + 'a,
         Eh: Handler<ListenerE, ()> + 'a,
-        Session1: 'a,
-        Session2: 'a,
-        H1: 'a,
-        H2: 'a,
-        HandlerE: 'a,
         ListenerE: Debug,
     {
+        let update_listener = Box::pin(update_listener);
+
         update_listener
-            .for_each_concurrent(None, move |update| async {
+            .for_each_concurrent(None, move |update| async move {
                 let update = match update {
                     Ok(update) => update,
                     Err(error) => {
@@ -133,7 +222,7 @@ where
                     UpdateKind::Message(message) => match message.chat.kind {
                         ChatKind::Private { .. } => {
                             if let Some(private_message_dp) =
-                                &mut self.private_message_dp
+                                &self.private_message_dp
                             {
                                 private_message_dp
                                     .dispatch(self.bot, message)
@@ -141,8 +230,7 @@ where
                             }
                         }
                         _ => {
-                            if let Some(message_handler) =
-                                &mut self.message_handler
+                            if let Some(message_handler) = &self.message_handler
                             {
                                 message_handler
                                     .handle(BasicHandlerCtx {
@@ -158,7 +246,7 @@ where
                         match message.chat.kind {
                             ChatKind::Private { .. } => {
                                 if let Some(private_edited_message_dp) =
-                                    &mut self.private_edited_message_dp
+                                    &self.private_edited_message_dp
                                 {
                                     private_edited_message_dp
                                         .dispatch(self.bot, message)
@@ -167,7 +255,7 @@ where
                             }
                             _ => {
                                 if let Some(edited_message_handler) =
-                                    &mut self.edited_message_handler
+                                    &self.edited_message_handler
                                 {
                                     edited_message_handler
                                         .handle(BasicHandlerCtx {
@@ -181,7 +269,7 @@ where
                     }
                     UpdateKind::ChannelPost(post) => {
                         if let Some(channel_post_handler) =
-                            &mut self.channel_post_handler
+                            &self.channel_post_handler
                         {
                             channel_post_handler
                                 .handle(BasicHandlerCtx {
@@ -193,7 +281,7 @@ where
                     }
                     UpdateKind::EditedChannelPost(post) => {
                         if let Some(edited_channel_post_handler) =
-                            &mut self.edited_channel_post_handler
+                            &self.edited_channel_post_handler
                         {
                             edited_channel_post_handler
                                 .handle(BasicHandlerCtx {
@@ -205,7 +293,7 @@ where
                     }
                     UpdateKind::InlineQuery(query) => {
                         if let Some(inline_query_handler) =
-                            &mut self.inline_query_handler
+                            &self.inline_query_handler
                         {
                             inline_query_handler
                                 .handle(BasicHandlerCtx {
@@ -217,7 +305,7 @@ where
                     }
                     UpdateKind::ChosenInlineResult(result) => {
                         if let Some(chosen_inline_result_handler) =
-                            &mut self.chosen_inline_result_handler
+                            &self.chosen_inline_result_handler
                         {
                             chosen_inline_result_handler
                                 .handle(BasicHandlerCtx {
@@ -229,7 +317,7 @@ where
                     }
                     UpdateKind::CallbackQuery(query) => {
                         if let Some(callback_query_handler) =
-                            &mut self.callback_query_handler
+                            &self.callback_query_handler
                         {
                             callback_query_handler
                                 .handle(BasicHandlerCtx {
@@ -241,7 +329,7 @@ where
                     }
                     UpdateKind::ShippingQuery(query) => {
                         if let Some(shipping_query_handler) =
-                            &mut self.shipping_query_handler
+                            &self.shipping_query_handler
                         {
                             shipping_query_handler
                                 .handle(BasicHandlerCtx {
@@ -253,7 +341,7 @@ where
                     }
                     UpdateKind::PreCheckoutQuery(query) => {
                         if let Some(pre_checkout_query_handler) =
-                            &mut self.pre_checkout_query_handler
+                            &self.pre_checkout_query_handler
                         {
                             pre_checkout_query_handler
                                 .handle(BasicHandlerCtx {
@@ -264,7 +352,7 @@ where
                         }
                     }
                     UpdateKind::Poll(poll) => {
-                        if let Some(poll_handler) = &mut self.poll_handler {
+                        if let Some(poll_handler) = &self.poll_handler {
                             poll_handler
                                 .handle(BasicHandlerCtx {
                                     bot: self.bot,
diff --git a/src/dispatching/session/mod.rs b/src/dispatching/session/mod.rs
index 04f41a5c..ec47ab25 100644
--- a/src/dispatching/session/mod.rs
+++ b/src/dispatching/session/mod.rs
@@ -84,7 +84,7 @@ where
     }
 
     /// Dispatches a single `message` from a private chat.
-    pub async fn dispatch<Upd>(&'a mut self, bot: &'a Bot, update: Upd)
+    pub async fn dispatch<Upd>(&'a self, bot: &'a Bot, update: Upd)
     where
         H: Handler<SessionHandlerCtx<'a, Upd, Session>, SessionState<Session>>,
         Upd: GetChatId,
diff --git a/src/dispatching/session/storage/in_mem_storage.rs b/src/dispatching/session/storage/in_mem_storage.rs
index 140ee133..3203093c 100644
--- a/src/dispatching/session/storage/in_mem_storage.rs
+++ b/src/dispatching/session/storage/in_mem_storage.rs
@@ -2,6 +2,7 @@ use async_trait::async_trait;
 
 use super::Storage;
 use std::collections::HashMap;
+use tokio::sync::Mutex;
 
 /// A memory storage based on a hash map. Stores all the sessions directly in
 /// RAM.
@@ -10,23 +11,23 @@ use std::collections::HashMap;
 /// All the sessions will be lost after you restart your bot. If you need to
 /// store them somewhere on a drive, you need to implement a storage
 /// communicating with a DB.
-#[derive(Clone, Debug, Eq, PartialEq, Default)]
+#[derive(Debug, Default)]
 pub struct InMemStorage<Session> {
-    map: HashMap<i64, Session>,
+    map: Mutex<HashMap<i64, Session>>,
 }
 
 #[async_trait(?Send)]
 #[async_trait]
 impl<Session> Storage<Session> for InMemStorage<Session> {
-    async fn remove_session(&mut self, chat_id: i64) -> Option<Session> {
-        self.map.remove(&chat_id)
+    async fn remove_session(&self, chat_id: i64) -> Option<Session> {
+        self.map.lock().await.remove(&chat_id)
     }
 
     async fn update_session(
-        &mut self,
+        &self,
         chat_id: i64,
         state: Session,
     ) -> Option<Session> {
-        self.map.insert(chat_id, state)
+        self.map.lock().await.insert(chat_id, state)
     }
 }
diff --git a/src/dispatching/session/storage/mod.rs b/src/dispatching/session/storage/mod.rs
index e3e12bbf..5bff11f6 100644
--- a/src/dispatching/session/storage/mod.rs
+++ b/src/dispatching/session/storage/mod.rs
@@ -18,14 +18,14 @@ pub trait Storage<Session> {
     ///
     /// Returns `None` if there wasn't such a session, `Some(session)` if a
     /// `session` was deleted.
-    async fn remove_session(&mut self, chat_id: i64) -> Option<Session>;
+    async fn remove_session(&self, chat_id: i64) -> Option<Session>;
 
     /// Updates a session with the specified `chat_id`.
     ///
     /// Returns `None` if there wasn't such a session, `Some(session)` if a
     /// `session` was updated.
     async fn update_session(
-        &mut self,
+        &self,
         chat_id: i64,
         session: Session,
     ) -> Option<Session>;