diff --git a/src/bot/events/guild-member-update/server-booster/validators/index.ts b/src/bot/events/guild-member-update/server-booster/validators/index.ts
deleted file mode 100644
index 9622c8c..0000000
--- a/src/bot/events/guild-member-update/server-booster/validators/index.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-import { DiscordAssert } from '@utils/discord'
-import { ServerBoosterMessage } from '../messages'
-
-export class ServerBooster extends ServerBoosterMessage {
-    static override BASE_PERMS = [
-        ...DiscordAssert.BASE_PERMS,
-    ]
-}
diff --git a/src/bot/events/message-create/channel/handlers/check-in.ts b/src/bot/events/message-create/channel/handlers/check-in.ts
index b2330ae..f438c59 100644
--- a/src/bot/events/message-create/channel/handlers/check-in.ts
+++ b/src/bot/events/message-create/channel/handlers/check-in.ts
@@ -19,20 +19,15 @@ const moduleName = getModuleName(EVENT_PATH, __filename)
 registerMessageHandler({
     desc: 'Handle messages in channel for Check In event.',
     errorTag: () => `${moduleName}: ${CheckIn.ERR.UnexpectedCheckIn}`,
-    match: msg => msg.channel.id === CHECKIN_CHANNEL,
+    match: msg => !msg.author.bot && msg.channel.id === CHECKIN_CHANNEL && msg.channel.type === ChannelType.GuildText,
     async exec(_, msg) {
         try {
-            if (!msg.guild)
+            if (!msg.guild || !msg.inGuild())
                 throw new CheckInError(CheckIn.ERR.NotGuild)
 
             const channel = msg.channel as TextChannel
             CheckIn.assertMissPerms(msg.guild.members.me!, channel)
 
-            if (channel.type !== ChannelType.GuildText)
-                return
-            if (msg.author.bot)
-                return
-
             await msg.delete()
             log.warn(`${channel.name}: deleted unauthorized message from '${msg.author.tag}'`)
         }
diff --git a/src/bot/events/message-create/im-fine/handlers/index.ts b/src/bot/events/message-create/im-fine/handlers/index.ts
index 54f21d9..578a47c 100644
--- a/src/bot/events/message-create/im-fine/handlers/index.ts
+++ b/src/bot/events/message-create/im-fine/handlers/index.ts
@@ -17,6 +17,9 @@ registerMessageHandler({
     errorTag: () => `${moduleName}: ${ImFine.ERR.UnexpectedImFine}`,
     match: msg => !msg.author.bot && msg.content.includes('fine'),
     async exec(_, msg) {
+        if (!msg.guild || !msg.inGuild())
+            throw new ImFineError(ImFine.ERR.NotGuild)
+
         await msg.reply('gua I\'m fine😅')
     },
 })
diff --git a/src/bot/events/guild-member-update/server-booster/handlers/index.ts b/src/bot/events/message-create/server-booster/handlers/index.ts
similarity index 56%
rename from src/bot/events/guild-member-update/server-booster/handlers/index.ts
rename to src/bot/events/message-create/server-booster/handlers/index.ts
index 104f06f..9afeca3 100644
--- a/src/bot/events/guild-member-update/server-booster/handlers/index.ts
+++ b/src/bot/events/message-create/server-booster/handlers/index.ts
@@ -1,8 +1,8 @@
 import type { TextChannel } from 'discord.js'
-import { AURA_FARMING_CHANNEL } from '@config/discord'
-import { registerGuildMemberUpdateHandler } from '@events/guild-member-update/registry'
+import { SYSTEM_ASHES_CHANNEL } from '@config/discord'
 import { EVENT_PATH } from '@events/index'
-import { getChannel, sendAsBot } from '@utils/discord'
+import { registerMessageHandler } from '@events/message-create/registry'
+import { sendAsBot } from '@utils/discord'
 import { DiscordBaseError } from '@utils/discord/error'
 import { getModuleName } from '@utils/io'
 import { ServerBooster } from '../validators'
@@ -15,25 +15,22 @@ export class ServerBoosterError extends DiscordBaseError {
 
 const moduleName = getModuleName(EVENT_PATH, __filename)
 
-registerGuildMemberUpdateHandler({
-    desc: 'Watches server booster for members on guild member update.',
+registerMessageHandler({
+    desc: 'Watches server boost system messages (including re-boosts).',
     errorTag: () => `${moduleName}: ${ServerBooster.ERR.UnexpectedServerBooster}`,
-    async exec(_, oldMember, newMember) {
+    match: msg => msg.system && msg.channelId === SYSTEM_ASHES_CHANNEL && !!msg.member && ServerBooster.isBoostSystemMessage(msg),
+    async exec(_, msg) {
         try {
-            if (!newMember.guild)
+            if (!msg.guild || !msg.inGuild())
                 throw new ServerBoosterError(ServerBooster.ERR.NotGuild)
 
-            const wasBoosting = !!oldMember.premiumSince
-            const isBoosting = !!newMember.premiumSince
-
-            const justBoosted = !wasBoosting && isBoosting
-            if (!justBoosted)
-                return
-
-            const channel = await getChannel(newMember.guild, AURA_FARMING_CHANNEL) as TextChannel
+            const channel = msg.channel as TextChannel
             ServerBooster.assertChannel(channel)
+            ServerBooster.assertMissPerms(msg.guild.members.me!, channel)
+            const member = msg.member!
+            ServerBooster.assertMember(member)
 
-            const embed = ServerBooster.sayDeeplyThanksTo(newMember)
+            const embed = ServerBooster.sayDeeplyThanksTo(member)
 
             await sendAsBot(null, channel, {
                 content: ServerBooster.MSG.SpecialThanks,
diff --git a/src/bot/events/guild-member-update/server-booster/messages/index.ts b/src/bot/events/message-create/server-booster/messages/index.ts
similarity index 100%
rename from src/bot/events/guild-member-update/server-booster/messages/index.ts
rename to src/bot/events/message-create/server-booster/messages/index.ts
diff --git a/src/bot/events/message-create/server-booster/validators/index.ts b/src/bot/events/message-create/server-booster/validators/index.ts
new file mode 100644
index 0000000..40d51aa
--- /dev/null
+++ b/src/bot/events/message-create/server-booster/validators/index.ts
@@ -0,0 +1,21 @@
+import type { Message } from 'discord.js'
+import { DiscordAssert } from '@utils/discord'
+import { MessageType } from 'discord.js'
+import { ServerBoosterMessage } from '../messages'
+
+export class ServerBooster extends ServerBoosterMessage {
+    static override BASE_PERMS = [
+        ...DiscordAssert.BASE_PERMS,
+    ]
+
+    static readonly DISCORD_BOOST_MESSAGES = [
+        MessageType.GuildBoost,
+        MessageType.GuildBoostTier1,
+        MessageType.GuildBoostTier2,
+        MessageType.GuildBoostTier3,
+    ]
+
+    static isBoostSystemMessage(message: Message): boolean {
+        return this.DISCORD_BOOST_MESSAGES.includes(message.type)
+    }
+}
diff --git a/src/bot/events/message-reaction-add/checkin/handlers/submitted.ts b/src/bot/events/message-reaction-add/checkin/handlers/submitted.ts
index 6215cac..e63cda7 100644
--- a/src/bot/events/message-reaction-add/checkin/handlers/submitted.ts
+++ b/src/bot/events/message-reaction-add/checkin/handlers/submitted.ts
@@ -21,7 +21,7 @@ registerReactionHandler({
         const message = reaction.message
         const guild = message.guild
         if (!guild || !message.inGuild())
-            return
+            throw new SubmittedCheckinError(Checkin.ERR.NotGuild)
 
         if (reaction.partial)
             await reaction.fetch()
diff --git a/src/config/discord.ts b/src/config/discord.ts
index 42ebd41..3528d8c 100644
--- a/src/config/discord.ts
+++ b/src/config/discord.ts
@@ -1,5 +1,6 @@
 import type { RoleManager } from 'discord.js'
 
+export const SYSTEM_ASHES_CHANNEL = '1405871418788548638'
 export const CHECKIN_CHANNEL = '1405165987288059944'
 export const AURA_FARMING_CHANNEL = '1405162471496351794'
 export const GRIND_ASHES_CHANNEL = '1405165926600409148'