diff --git a/Services/FlexMigrator.php b/Services/FlexMigrator.php
index 90dc5c7..920bb70 100644
--- a/Services/FlexMigrator.php
+++ b/Services/FlexMigrator.php
@@ -173,6 +173,7 @@ public function copyNewTemplateFiles(string $projectDir): void
     public function migrateEnvFile(string $projectDir): void
     {
         $envPath = $projectDir . '/.env';
+        $envLocalPath = $projectDir . '/.env.local';
 
         if (!is_file($envPath)) {
             file_put_contents($envPath, self::ENV_DEFAULT);
@@ -180,7 +181,10 @@ public function migrateEnvFile(string $projectDir): void
             return;
         }
 
-        rename($envPath, $envPath . '.local');
+        if (!is_file($envLocalPath)) {
+            rename($envPath, $envLocalPath);
+        }
+
         file_put_contents($envPath, self::ENV_DEFAULT);
     }
 
diff --git a/Tests/Services/FlexMigratorTest.php b/Tests/Services/FlexMigratorTest.php
index 06bc74f..7dacf63 100644
--- a/Tests/Services/FlexMigratorTest.php
+++ b/Tests/Services/FlexMigratorTest.php
@@ -87,6 +87,27 @@ public function testMigrateEnvExistingEnv(): void
         $fs->remove($tmpDir);
     }
 
+    public function testMigrateEnvDoesNotOverwriteExistingEnvLocal(): void
+    {
+        $tmpDir = sys_get_temp_dir() . '/flex-migrator-test';
+        $fs = new Filesystem();
+        $fs->mkdir($tmpDir);
+        $fs->dumpFile($tmpDir . '/.env', 'DATABASE_URL=mysql://user:pass@localhost/real_db');
+        $fs->dumpFile($tmpDir . '/.env.local', 'DATABASE_URL=mysql://user:pass@localhost/real_db');
+
+        $flexMigrator = new FlexMigrator();
+
+        $flexMigrator->migrateEnvFile($tmpDir);
+
+        static::assertFileExists($tmpDir . '/.env');
+        static::assertFileExists($tmpDir . '/.env.local');
+        static::assertStringContainsString('###> symfony/lock ###', (string) file_get_contents($tmpDir . '/.env'));
+        // The existing .env.local must not be overwritten
+        static::assertSame('DATABASE_URL=mysql://user:pass@localhost/real_db', (string) file_get_contents($tmpDir . '/.env.local'));
+
+        $fs->remove($tmpDir);
+    }
+
     public static function composerCases(): \Generator
     {
         yield 'no repos' => [