diff --git a/CHANGELOG b/CHANGELOG
index 45f26c24cbb..cc49206d203 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -54,6 +54,7 @@ CHANGELOG Roundcube Webmail
 - Fix PHP warning when handling shared namespace with empty prefix (#5420)
 - Fix so folders list is scrolled to the selected folder on page load (#5424)
 - Fix so when moving to Trash we make sure the folder exists (#5192)
+- Fix displaying size of attachments with zero size
 
 RELEASE 1.2.1
 -------------
diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index c2007c7d76f..fc6ea575d30 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -2350,6 +2350,10 @@ public function message_part_size($part)
         else {
             $size = $part->size;
 
+            if ($size === 0) {
+                $part->exact_size = true;
+            }
+
             if ($part->encoding == 'base64') {
                 $size = $size / 1.33;
             }
diff --git a/program/steps/mail/show.inc b/program/steps/mail/show.inc
index de54eb4a6f2..e1909a4d966 100644
--- a/program/steps/mail/show.inc
+++ b/program/steps/mail/show.inc
@@ -202,10 +202,7 @@ function rcmail_message_attachments($attrib)
                     $title = '';
                 }
 
-                if ($attach_prop->size) {
-                    $size = ' ' . html::span('attachment-size', '(' . rcube::Q($filesize) . ')');
-                }
-
+                $size     = ' ' . html::span('attachment-size', '(' . rcube::Q($filesize) . ')');
                 $mimetype = rcmail_fix_mimetype($attach_prop->mimetype);
                 $class    = rcube_utils::file2class($mimetype, $filename);
                 $id       = 'attach' . $attach_prop->mime_id;