diff --git a/packages/backend/migration/1738776889000-setFederationAvatarShape.js b/packages/backend/migration/1738776889000-setFederationAvatarShape.js
index c735993cf9..801ba26b9a 100644
--- a/packages/backend/migration/1738776889000-setFederationAvatarShape.js
+++ b/packages/backend/migration/1738776889000-setFederationAvatarShape.js
@@ -7,8 +7,8 @@ export class setFederationAvatarShape1738776889000 {
     name = 'setFederationAvatarShape1738776889000'
 
     async up(queryRunner) {
-				await queryRunner.query(`ALTER TABLE "user" ADD "setFederationAvatarShape" boolean NOT NULL DEFAULT false`);
-				await queryRunner.query(`ALTER TABLE "user" ADD "isSquareAvatars" boolean NOT NULL DEFAULT false`);
+				await queryRunner.query(`ALTER TABLE "user" ADD "setFederationAvatarShape" boolean DEFAULT null`, undefined);
+				await queryRunner.query(`ALTER TABLE "user" ADD "isSquareAvatars" boolean DEFAULT null`, undefined);
     }
 
     async down(queryRunner) {
diff --git a/packages/backend/src/core/activitypub/ApRendererService.ts b/packages/backend/src/core/activitypub/ApRendererService.ts
index 21de925792..54349210b0 100644
--- a/packages/backend/src/core/activitypub/ApRendererService.ts
+++ b/packages/backend/src/core/activitypub/ApRendererService.ts
@@ -543,8 +543,8 @@ export class ApRendererService {
 			publicKey: this.renderKey(user, keypair, '#main-key'),
 			isCat: user.isCat,
 			attachment: attachment.length ? attachment : undefined,
-			setFederationAvatarShape: user.setFederationAvatarShape,
-			isSquareAvatars: user.isSquareAvatars,
+			setFederationAvatarShape: user.setFederationAvatarShape ? user.setFederationAvatarShape : undefined,
+			isSquareAvatars: user.isSquareAvatars ? user.isSquareAvatars : undefined,
 		};
 
 		if (user.movedToUri) {
diff --git a/packages/backend/src/core/entities/UserEntityService.ts b/packages/backend/src/core/entities/UserEntityService.ts
index 972576aa8f..184106f879 100644
--- a/packages/backend/src/core/entities/UserEntityService.ts
+++ b/packages/backend/src/core/entities/UserEntityService.ts
@@ -553,8 +553,8 @@ export class UserEntityService implements OnModuleInit {
 					displayOrder: r.displayOrder,
 				})),
 			) : undefined,
-			setFederationAvatarShape: user.setFederationAvatarShape,
-			isSquareAvatars: user.isSquareAvatars,
+			setFederationAvatarShape: user.setFederationAvatarShape || undefined,
+			isSquareAvatars: user.isSquareAvatars || undefined,
 
 			...(isDetailed ? {
 				url: profile!.url,
diff --git a/packages/backend/src/models/User.ts b/packages/backend/src/models/User.ts
index c9c9957c4d..caa00d41f6 100644
--- a/packages/backend/src/models/User.ts
+++ b/packages/backend/src/models/User.ts
@@ -279,14 +279,14 @@ export class MiUser {
 	public token: string | null;
 
 	@Column('boolean', {
-		default: false,
+		nullable: true,
 	})
-	public setFederationAvatarShape: boolean;
+	public setFederationAvatarShape: boolean | null;
 
 	@Column('boolean', {
-		default: false,
+		nullable: true,
 	})
-	public isSquareAvatars: boolean;
+	public isSquareAvatars: boolean | null;
 
 	constructor(data: Partial<MiUser>) {
 		if (data == null) return;
diff --git a/packages/backend/src/models/json-schema/user.ts b/packages/backend/src/models/json-schema/user.ts
index 04297187a9..1870c7436b 100644
--- a/packages/backend/src/models/json-schema/user.ts
+++ b/packages/backend/src/models/json-schema/user.ts
@@ -201,11 +201,11 @@ export const packedUserLiteSchema = {
 		},
 		setFederationAvatarShape: {
 			type: 'boolean',
-			nullable: false, optional: false,
+			nullable: false, optional: true,
 		},
 		isSquareAvatars: {
 			type: 'boolean',
-			nullable: false, optional: false,
+			nullable: false, optional: true,
 		},
 	},
 } as const;
diff --git a/packages/backend/src/server/api/endpoints/admin/show-user.ts b/packages/backend/src/server/api/endpoints/admin/show-user.ts
index 22d324b5b4..941d75456e 100644
--- a/packages/backend/src/server/api/endpoints/admin/show-user.ts
+++ b/packages/backend/src/server/api/endpoints/admin/show-user.ts
@@ -179,11 +179,11 @@ export const meta = {
 			},
 			setFederationAvatarShape: {
 				type: 'boolean',
-				optional: false, nullable: false,
+				optional: true, nullable: true,
 			},
 			isSquareAvatars: {
 				type: 'boolean',
-				optional: false, nullable: false,
+				optional: true, nullable: true,
 			},
 		},
 	},
diff --git a/packages/backend/src/server/api/endpoints/i/update.ts b/packages/backend/src/server/api/endpoints/i/update.ts
index 576d9adca6..471429ee60 100644
--- a/packages/backend/src/server/api/endpoints/i/update.ts
+++ b/packages/backend/src/server/api/endpoints/i/update.ts
@@ -228,8 +228,8 @@ export const paramDef = {
 			uniqueItems: true,
 			items: { type: 'string' },
 		},
-		setFederationAvatarShape: { type: 'boolean' },
-		isSquareAvatars: { type: 'boolean' },
+		setFederationAvatarShape: { type: 'boolean', nullable: true },
+		isSquareAvatars: { type: 'boolean', nullable: true },
 	},
 } as const;
 
diff --git a/packages/cherrypick-js/src/autogen/types.ts b/packages/cherrypick-js/src/autogen/types.ts
index dc5cd55478..486a5d9de2 100644
--- a/packages/cherrypick-js/src/autogen/types.ts
+++ b/packages/cherrypick-js/src/autogen/types.ts
@@ -4134,8 +4134,8 @@ export type components = {
           iconUrl: string | null;
           displayOrder: number;
         })[];
-      setFederationAvatarShape: boolean;
-      isSquareAvatars: boolean;
+      setFederationAvatarShape?: boolean;
+      isSquareAvatars?: boolean;
     };
     UserDetailedNotMeOnly: {
       /** Format: url */
@@ -10724,8 +10724,8 @@ export type operations = {
                 expiresAt: string | null;
                 roleId: string;
               })[];
-            setFederationAvatarShape: boolean;
-            isSquareAvatars: boolean;
+            setFederationAvatarShape?: boolean | null;
+            isSquareAvatars?: boolean | null;
           };
         };
       };
@@ -22245,8 +22245,8 @@ export type operations = {
           };
           emailNotificationTypes?: string[];
           alsoKnownAs?: string[];
-          setFederationAvatarShape?: boolean;
-          isSquareAvatars?: boolean;
+          setFederationAvatarShape?: boolean | null;
+          isSquareAvatars?: boolean | null;
         };
       };
     };
diff --git a/packages/frontend/src/boot/main-boot.ts b/packages/frontend/src/boot/main-boot.ts
index e3bc4ba794..44c266aad7 100644
--- a/packages/frontend/src/boot/main-boot.ts
+++ b/packages/frontend/src/boot/main-boot.ts
@@ -425,7 +425,7 @@ export async function mainBoot() {
 			signout();
 		});
 
-		// 프로필 아이콘 모양 설정 연합
+		// 프로필 아이콘 모양 설정 연합 초기화
 		if ($i.policies.canSetFederationAvatarShape && defaultStore.state.setFederationAvatarShape) {
 			await misskeyApi('i/update', {
 				setFederationAvatarShape: true,