diff --git a/mail/src/main/java/org/bouncycastle/mail/smime/handlers/multipart_signed.java b/mail/src/main/java/org/bouncycastle/mail/smime/handlers/multipart_signed.java
index 3abd395f01..7fba22651c 100644
--- a/mail/src/main/java/org/bouncycastle/mail/smime/handlers/multipart_signed.java
+++ b/mail/src/main/java/org/bouncycastle/mail/smime/handlers/multipart_signed.java
@@ -207,7 +207,7 @@ public void writeln(String s)
         {
             try
             {
-                byte abyte0[] = Strings.toByteArray(s);
+                byte abyte0[] = Strings.toUTF8ByteArray(s);
                 super.out.write(abyte0);
                 super.out.write(newline);
             }