diff --git a/src/source/empty.rs b/src/source/empty.rs
index f3a90604..2a465da6 100644
--- a/src/source/empty.rs
+++ b/src/source/empty.rs
@@ -43,7 +43,7 @@ where
 {
     #[inline]
     fn current_frame_len(&self) -> Option<usize> {
-        Some(0)
+        None
     }
 
     #[inline]