diff --git a/io/bufio.ts b/io/bufio.ts
index aec053e6ac937..815c94eed8cd2 100644
--- a/io/bufio.ts
+++ b/io/bufio.ts
@@ -17,7 +17,7 @@ const LF = charCode("\n");
 
 export class BufferFullError extends Error {
   name = "BufferFullError";
-  constructor(readonly partial: Uint8Array) {
+  constructor(public partial: Uint8Array) {
     super("Buffer full");
   }
 }