diff --git a/lib/internal/webstreams/adapters.js b/lib/internal/webstreams/adapters.js
index 38e327fad2081a..1ade5d32951ff5 100644
--- a/lib/internal/webstreams/adapters.js
+++ b/lib/internal/webstreams/adapters.js
@@ -185,7 +185,12 @@ function newWritableStreamFromStreamWritable(streamWritable, options = kEmptyObj
   const strategy =
     streamWritable.writableObjectMode ?
       new CountQueuingStrategy({ highWaterMark }) :
-      { highWaterMark };
+      {
+        highWaterMark,
+        size(chunk) {
+          return chunk?.byteLength ?? chunk?.length ?? 1;
+        },
+      };
 
   let controller;
   let backpressurePromise;