diff --git a/packages/backend/src/db/meilisearch.ts b/packages/backend/src/db/meilisearch.ts
index a98c3e80ce..6762986284 100644
--- a/packages/backend/src/db/meilisearch.ts
+++ b/packages/backend/src/db/meilisearch.ts
@@ -154,7 +154,7 @@ function timestampToUnix(timestamp: string) {
 	if (unix === 0) {
 		// Try to parse the timestamp as JavaScript Date
 		const date = Date.parse(timestamp);
-		if (isNaN(date)) return 0;
+		if (Number.isNaN(date)) return 0;
 		unix = date / 1000;
 	}
 
diff --git a/packages/backend/src/server/web/index.ts b/packages/backend/src/server/web/index.ts
index d3c751acc6..12119ef3c3 100644
--- a/packages/backend/src/server/web/index.ts
+++ b/packages/backend/src/server/web/index.ts
@@ -301,12 +301,12 @@ const getFeed = async (
 		return;
 	}
 	let thread = parseInt(threadDepth, 10);
-	if (isNaN(thread) || thread < 0 || thread > 30) {
+	if (Number.isNaN(thread) || thread < 0 || thread > 30) {
 		thread = 3;
 	}
 	let history = parseInt(historyCount, 10);
 	//cant be 0 here or it will get all posts
-	if (isNaN(history) || history <= 0 || history > 30) {
+	if (Number.isNaN(history) || history <= 0 || history > 30) {
 		history = 20;
 	}
 	return (
@@ -315,9 +315,9 @@ const getFeed = async (
 			user,
 			thread,
 			history,
-			!isNaN(noteInTitle),
-			isNaN(noRenotes),
-			isNaN(noReplies),
+			!Number.isNaN(noteInTitle),
+			Number.isNaN(noRenotes),
+			Number.isNaN(noReplies),
 		))
 	);
 };
diff --git a/packages/backend/src/services/note/create.ts b/packages/backend/src/services/note/create.ts
index 1e57d20f00..ed6ab932c1 100644
--- a/packages/backend/src/services/note/create.ts
+++ b/packages/backend/src/services/note/create.ts
@@ -201,7 +201,7 @@ export default async (
 		const now = new Date();
 		if (
 			!data.createdAt ||
-			isNaN(data.createdAt.getTime()) ||
+			Number.isNaN(data.createdAt.getTime()) ||
 			data.createdAt > now
 		)
 			data.createdAt = now;
@@ -782,7 +782,7 @@ async function insertNote(
 				await transactionalEntityManager.insert(Note, insert);
 
 				let expiresAt: Date | null;
-				if (!data.poll.expiresAt || isNaN(data.poll.expiresAt.getTime())) {
+				if (!data.poll.expiresAt || Number.isNaN(data.poll.expiresAt.getTime())) {
 					expiresAt = null;
 				} else {
 					expiresAt = data.poll.expiresAt;
diff --git a/packages/client/src/components/mfm.ts b/packages/client/src/components/mfm.ts
index 5dbf710118..8de385c40f 100644
--- a/packages/client/src/components/mfm.ts
+++ b/packages/client/src/components/mfm.ts
@@ -61,7 +61,7 @@ export default defineComponent({
 		const validNumber = (n: string | null | undefined) => {
 			if (n == null) return null;
 			const parsed = parseFloat(n);
-			return !isNaN(parsed) && isFinite(parsed) && parsed > 0;
+			return !Number.isNaN(parsed) && Number.isFinite(parsed) && parsed > 0;
 		};
 		// const validEase = (e: string | null | undefined) => {
 		// 	if (e == null) return null;