diff --git a/src/client/app/common/views/components/poll.vue b/src/client/app/common/views/components/poll.vue
index 660247edbc..4fe51d219b 100644
--- a/src/client/app/common/views/components/poll.vue
+++ b/src/client/app/common/views/components/poll.vue
@@ -21,6 +21,7 @@
 
 <script lang="ts">
 import Vue from 'vue';
+import { sum } from '../../../../../prelude/array';
 export default Vue.extend({
 	props: ['note'],
 	data() {
@@ -33,7 +34,7 @@ export default Vue.extend({
 			return this.note.poll;
 		},
 		total(): number {
-			return this.poll.choices.reduce((a, b) => a + b.votes, 0);
+			return sum(this.poll.choices.map(x => x.votes));
 		},
 		isVoted(): boolean {
 			return this.poll.choices.some(c => c.isVoted);
diff --git a/src/client/app/desktop/views/components/note-detail.vue b/src/client/app/desktop/views/components/note-detail.vue
index a61a004a85..1e068bd1cd 100644
--- a/src/client/app/desktop/views/components/note-detail.vue
+++ b/src/client/app/desktop/views/components/note-detail.vue
@@ -86,6 +86,7 @@ import MkRenoteFormWindow from './renote-form-window.vue';
 import MkNoteMenu from '../../../common/views/components/note-menu.vue';
 import MkReactionPicker from '../../../common/views/components/reaction-picker.vue';
 import XSub from './notes.note.sub.vue';
+import { sum } from '../../../../../prelude/array';
 
 export default Vue.extend({
 	components: {
@@ -122,9 +123,7 @@ export default Vue.extend({
 		},
 		reactionsCount(): number {
 			return this.p.reactionCounts
-				? Object.keys(this.p.reactionCounts)
-					.map(key => this.p.reactionCounts[key])
-					.reduce((a, b) => a + b)
+				? sum(Object.values(this.p.reactionCounts))
 				: 0;
 		},
 		title(): string {
diff --git a/src/client/app/desktop/views/components/notes.note.vue b/src/client/app/desktop/views/components/notes.note.vue
index 1d6b2048ba..75d6ebd628 100644
--- a/src/client/app/desktop/views/components/notes.note.vue
+++ b/src/client/app/desktop/views/components/notes.note.vue
@@ -78,6 +78,7 @@ import MkRenoteFormWindow from './renote-form-window.vue';
 import MkNoteMenu from '../../../common/views/components/note-menu.vue';
 import MkReactionPicker from '../../../common/views/components/reaction-picker.vue';
 import XSub from './notes.note.sub.vue';
+import { sum } from '../../../../../prelude/array';
 
 function focus(el, fn) {
 	const target = fn(el);
@@ -120,9 +121,7 @@ export default Vue.extend({
 
 		reactionsCount(): number {
 			return this.p.reactionCounts
-				? Object.keys(this.p.reactionCounts)
-					.map(key => this.p.reactionCounts[key])
-					.reduce((a, b) => a + b)
+				? sum(Object.values(this.p.reactionCounts))
 				: 0;
 		},
 
diff --git a/src/client/app/mobile/views/components/note-detail.vue b/src/client/app/mobile/views/components/note-detail.vue
index 10ff3fcc09..d48d9a7790 100644
--- a/src/client/app/mobile/views/components/note-detail.vue
+++ b/src/client/app/mobile/views/components/note-detail.vue
@@ -85,6 +85,7 @@ import parse from '../../../../../mfm/parse';
 import MkNoteMenu from '../../../common/views/components/note-menu.vue';
 import MkReactionPicker from '../../../common/views/components/reaction-picker.vue';
 import XSub from './note.sub.vue';
+import { sum } from '../../../../../prelude/array';
 
 export default Vue.extend({
 	components: {
@@ -123,9 +124,7 @@ export default Vue.extend({
 
 		reactionsCount(): number {
 			return this.p.reactionCounts
-				? Object.keys(this.p.reactionCounts)
-					.map(key => this.p.reactionCounts[key])
-					.reduce((a, b) => a + b)
+				? sum(Object.values(this.p.reactionCounts))
 				: 0;
 		},
 
diff --git a/src/client/app/mobile/views/components/note.vue b/src/client/app/mobile/views/components/note.vue
index 9bd4a83ecb..907e728984 100644
--- a/src/client/app/mobile/views/components/note.vue
+++ b/src/client/app/mobile/views/components/note.vue
@@ -70,6 +70,7 @@ import parse from '../../../../../mfm/parse';
 import MkNoteMenu from '../../../common/views/components/note-menu.vue';
 import MkReactionPicker from '../../../common/views/components/reaction-picker.vue';
 import XSub from './note.sub.vue';
+import { sum } from '../../../../../prelude/array';
 
 export default Vue.extend({
 	components: {
@@ -100,9 +101,7 @@ export default Vue.extend({
 
 		reactionsCount(): number {
 			return this.p.reactionCounts
-				? Object.keys(this.p.reactionCounts)
-					.map(key => this.p.reactionCounts[key])
-					.reduce((a, b) => a + b)
+				? sum(Object.values(this.p.reactionCounts))
 				: 0;
 		},
 
diff --git a/src/prelude/array.ts b/src/prelude/array.ts
index abef6ca039..54f7081712 100644
--- a/src/prelude/array.ts
+++ b/src/prelude/array.ts
@@ -21,3 +21,7 @@ export function erase<T>(x: T, xs: T[]): T[] {
 export function unique<T>(xs: T[]): T[] {
 	return [...new Set(xs)];
 }
+
+export function sum(xs: number[]): number {
+	return xs.reduce((a, b) => a + b, 0);
+}