diff --git a/pkg/io/binaryWriter.go b/pkg/io/binaryWriter.go
index 5f234c1b4..dc563b149 100644
--- a/pkg/io/binaryWriter.go
+++ b/pkg/io/binaryWriter.go
@@ -143,7 +143,11 @@ func (w *BinWriter) WriteVarBytes(b []byte) {
 
 // WriteString writes a variable length string into the underlying io.Writer.
 func (w *BinWriter) WriteString(s string) {
-	w.WriteVarBytes([]byte(s))
+	w.WriteVarUint(uint64(len(s)))
+	if w.Err != nil {
+		return
+	}
+	_, w.Err = io.WriteString(w.w, s)
 }
 
 // Grow tries to increase underlying buffer capacity so that at least n bytes