diff --git a/CHANGELOG b/CHANGELOG
index 674e57948..40f000b5d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -6,6 +6,7 @@ CHANGELOG Roundcube Webmail
 - Password: Fix compatibility with PHP 7+ in cpanel_webmail driver (#5820)
 - Managesieve: Fix parsing dot-staffed lines in multiline text (#5838)
 - Managesieve: Fix AM/PM suffix in vacation time selectors
+- Managesieve: Fix bug where 'exists' operator was reset to 'contains' (#5899)
 - Remove non-printable characters from filenames on download/display (#5880)
 - Fix decoding non-ascii attachment names from TNEF attachments (#5646, #5799)
 - Fix uninitialized string offset in rcube_utils::bin2ascii() and make sure rcube_utils::random_bytes() result has always requested length (#5788)
diff --git a/plugins/managesieve/Changelog b/plugins/managesieve/Changelog
index 6cae23b3a..5a61f3d36 100644
--- a/plugins/managesieve/Changelog
+++ b/plugins/managesieve/Changelog
@@ -1,5 +1,6 @@
 - Fix parsing dot-staffed lines in multiline text (#5838)
 - Fix AM/PM suffix in vacation time selectors
+- Fix bug where 'exists' operator was reset to 'contains' (#5899)
 
 * version 8.9 [2017-05-22]
 -----------------------------------------------------------
diff --git a/plugins/managesieve/managesieve.js b/plugins/managesieve/managesieve.js
index d1f259b22..3eded8077 100644
--- a/plugins/managesieve/managesieve.js
+++ b/plugins/managesieve/managesieve.js
@@ -677,7 +677,7 @@ function rule_header_select(id)
     dateheader.style.display = h == 'date' ? '' : 'none';
 
   $('[value="exists"],[value="notexists"]', rule).prop('disabled', h == 'string');
-  if (!rule.val() || rule.val().match(/^(exists|notexists)$/))
+  if (!rule.val())
     rule.val('contains');
 
   rule_op_select(op, id, h);