diff --git a/src/steps/processMapFile.ts b/src/steps/processMapFile.ts
index c69d7b1a..5f3c6216 100644
--- a/src/steps/processMapFile.ts
+++ b/src/steps/processMapFile.ts
@@ -12,7 +12,7 @@ type TocItem = {
 
 type TocItems = TocItem[];
 
-export async function prepareMapFile(): void {
+export async function prepareMapFile(): Promise<void> {
     const {output: outputFolderPath} = ArgvService.getConfig();
 
     const navigationPathsWithoutExtensions = TocService.getNavigationPaths().map((path) => {