diff --git a/lib/src/db.rs b/lib/src/db.rs
index 2336be0..f97e09d 100644
--- a/lib/src/db.rs
+++ b/lib/src/db.rs
@@ -91,7 +91,7 @@ where
 
         let mut zencoder = zstd::stream::raw::Encoder::new(self.compress_lvl).str_err()?;
         zencoder
-            .set_pledged_src_size(item_data.len() as u64)
+            .set_pledged_src_size(Some(item_data.len() as u64))
             .str_err()?;
 
         self.cur_buf_raw.set_position(0);