diff --git a/internal/prefixcollector/collector_file_output_test.go b/internal/prefixcollector/collector_file_output_test.go
index 9473a35..b335f70 100644
--- a/internal/prefixcollector/collector_file_output_test.go
+++ b/internal/prefixcollector/collector_file_output_test.go
@@ -91,7 +91,7 @@ func (eps *ExcludedPrefixesSuite) testCollectorWithFileOutput(ctx context.Contex
 	ctx, cancel := context.WithTimeout(ctx, time.Second)
 	defer cancel()
 
-	watcher, errCh := eps.watchFile(ctx, prefixesFilePath, len(sources))
+	watcher, errCh := eps.watchFile(ctx, prefixesFilePath, len(sources)+1)
 
 	go collector.Serve(ctx)