diff --git a/logger.go b/logger.go
index 3cbc5ac..ae619ae 100644
--- a/logger.go
+++ b/logger.go
@@ -25,7 +25,7 @@ type Logger struct {
 func New(opts *Options) *Logger {
 	l := &Logger{}
 	// set a default filename encoder if log file is enabled
-	if !opts.DisableFile && len(opts.Output) > 0 {
+	if !opts.DisableFile && len(opts.Output) > 0 && opts.FilenameEncoder == nil {
 		opts.FilenameEncoder = DefaultFilenameEncoder
 	}