diff --git a/packages/backend/migration/1748128176881-add_instance_foreign_keys.js b/packages/backend/migration/1748128176881-add_instance_foreign_keys.js
index 9a970699a0..2c2383c50f 100644
--- a/packages/backend/migration/1748128176881-add_instance_foreign_keys.js
+++ b/packages/backend/migration/1748128176881-add_instance_foreign_keys.js
@@ -15,10 +15,19 @@ export class AddInstanceForeignKeys1748128176881 {
 	name = 'AddInstanceForeignKeys1748128176881'
 
 	async up(queryRunner) {
-		// Fix-up: Sharkey versions in early-mid 2025 could federate with HTTP URLs, which would produce a user with no matching instance.
-		// These users are fundamentally broken and can just be removed, which ensures that the FK can create without conflicts.
-		// But we must also *preserve* those with a matching registered instance, as FireFish allowed federation over HTTP and some older instances may have fully-populated users.
-		await queryRunner.query(`DELETE FROM "user" WHERE "uri" LIKE 'http:%' AND NOT EXISTS (select 1 from "instance" where "instance"."host" = "user"."host")`);
+		// Fix-up: Some older instances have users without a matching instance entry
+		await queryRunner.query(`
+			INSERT INTO "instance" ("id", "host", "firstRetrievedAt")
+			SELECT
+					MIN("id"),
+					"host",
+					COALESCE(MIN("lastFetchedAt"), CURRENT_TIMESTAMP)
+			FROM "user"
+			WHERE
+					"host" IS NOT NULL AND
+					NOT EXISTS (select 1 from "instance" where "instance"."host" = "user"."host")
+			GROUP BY "host"
+		`);
 
 		await queryRunner.query(`ALTER TABLE "user" ADD CONSTRAINT "FK_user_host" FOREIGN KEY ("host") REFERENCES "instance"("host") ON DELETE CASCADE ON UPDATE NO ACTION`);
 		await queryRunner.query(`ALTER TABLE "note" ADD CONSTRAINT "FK_note_userHost" FOREIGN KEY ("userHost") REFERENCES "instance"("host") ON DELETE CASCADE ON UPDATE NO ACTION`);