diff --git a/CHANGELOG b/CHANGELOG
index ee2af5f33..6a8449708 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 CHANGELOG RoundCube Webmail
 ===========================
 
+- Use default_charset for bodies of messages without charset definition (#1486187)
 - Password: added cPanel driver
 - Fix return to first page from e-mail screen (#1486105)
 - Fix handling HTML comments in HTML messages (#1486189)
diff --git a/program/include/rcube_imap.php b/program/include/rcube_imap.php
index 6e98b208a..d1021fd98 100644
--- a/program/include/rcube_imap.php
+++ b/program/include/rcube_imap.php
@@ -1554,7 +1554,7 @@ class rcube_imap
     // convert charset (if text or message part)
     if ($o_part->ctype_primary=='text' || $o_part->ctype_primary=='message') {
       // assume default if no charset specified
-      if (empty($o_part->charset))
+      if (empty($o_part->charset) || strtolower($o_part->charset) == 'us-ascii')
         $o_part->charset = $this->default_charset;
 
       $body = rcube_charset_convert($body, $o_part->charset);