diff --git a/ets2panda/linter/homecheck/src/checker/migration/CustomBuilderCheck.ts b/ets2panda/linter/homecheck/src/checker/migration/CustomBuilderCheck.ts
index e5591c8c30f4830a0e1172b53e25bcc1efb0802a..567db2a554f776510a36cd9158ec2eefb08f7278 100644
--- a/ets2panda/linter/homecheck/src/checker/migration/CustomBuilderCheck.ts
+++ b/ets2panda/linter/homecheck/src/checker/migration/CustomBuilderCheck.ts
@@ -228,7 +228,7 @@ export class CustomBuilderCheck implements BaseChecker {
         const increaseSpaces = FixUtils.getIndentWidth(sourceFile, fixPosition.startLine);
         const space = ' ';
 
-        let res = `() => {${eol}`;
+        let res = `(): void => {${eol}`;
         const originalLineStrs = originalText.split(eol);
         res += `${space.repeat(startLineIndent + increaseSpaces)}${originalLineStrs[0]}${eol}`;
         for (let index = 1; index < originalLineStrs.length; index++) {