diff --git a/packages/backend/src/core/NoteCreateService.ts b/packages/backend/src/core/NoteCreateService.ts
index 631d7074bd..d51315f71f 100644
--- a/packages/backend/src/core/NoteCreateService.ts
+++ b/packages/backend/src/core/NoteCreateService.ts
@@ -627,6 +627,14 @@ export class NoteCreateService implements OnApplicationShutdown {
 			userHost: user.host,
 		});
 
+		// should really not happen, but better safe than sorry
+		if (data.reply?.id === insert.id) {
+			throw new Error("A note can't reply to itself");
+		}
+		if (data.renote?.id === insert.id) {
+			throw new Error("A note can't renote itself");
+		}
+
 		if (data.uri != null) insert.uri = data.uri;
 		if (data.url != null) insert.url = data.url;
 
diff --git a/packages/backend/src/core/NoteEditService.ts b/packages/backend/src/core/NoteEditService.ts
index 399461dd70..6949136e69 100644
--- a/packages/backend/src/core/NoteEditService.ts
+++ b/packages/backend/src/core/NoteEditService.ts
@@ -299,6 +299,10 @@ export class NoteEditService implements OnApplicationShutdown {
 		}
 
 		if (data.renote) {
+			if (data.renote.id === oldnote.id) {
+				throw new Error("A note can't renote itself");
+			}
+
 			switch (data.renote.visibility) {
 				case 'public':
 					// public noteは無条件にrenote可能
diff --git a/packages/backend/src/core/activitypub/models/ApNoteService.ts b/packages/backend/src/core/activitypub/models/ApNoteService.ts
index 6d9dc86c16..ad7b3b145c 100644
--- a/packages/backend/src/core/activitypub/models/ApNoteService.ts
+++ b/packages/backend/src/core/activitypub/models/ApNoteService.ts
@@ -251,7 +251,7 @@ export class ApNoteService {
 			> => {
 				if (typeof uri !== 'string' || !/^https?:/.test(uri)) return { status: 'permerror' };
 				try {
-					const res = await this.resolveNote(uri);
+					const res = await this.resolveNote(uri, { resolver });
 					if (res == null) return { status: 'permerror' };
 					return { status: 'ok', res };
 				} catch (e) {
@@ -478,7 +478,7 @@ export class ApNoteService {
 			> => {
 				if (!/^https?:/.test(uri)) return { status: 'permerror' };
 				try {
-					const res = await this.resolveNote(uri);
+					const res = await this.resolveNote(uri, { resolver });
 					if (res == null) return { status: 'permerror' };
 					return { status: 'ok', res };
 				} catch (e) {