diff --git a/CHANGELOG b/CHANGELOG
index 0b56cd681..cd10b5cb8 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -29,6 +29,7 @@ CHANGELOG Roundcube Webmail
 - Fix so *-request@ addresses in Sender: header are also ignored on reply-all (#1490452)
 - Update to TinyMCE 4.1.10 (#1490405)
 - Fix draft removal after a message is sent and storing sent message is disabled (#1490467)
+- Fix so imap folder attribute comparisons are case-insensitive (#1490466)
 
 RELEASE 1.1.2
 -------------
diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index 580ac59b3..f00101a6a 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -1586,7 +1586,7 @@ class rcmail extends rcube
             // skip folders in which it isn't possible to create subfolders
             if (!empty($opts['skip_noinferiors'])) {
                 $attrs = $this->storage->folder_attributes($folder['id']);
-                if ($attrs && in_array('\\Noinferiors', $attrs)) {
+                if ($attrs && in_array_nocase('\\Noinferiors', $attrs)) {
                     continue;
                 }
             }
diff --git a/program/lib/Roundcube/bootstrap.php b/program/lib/Roundcube/bootstrap.php
index 2b7682b65..2e5d9e678 100644
--- a/program/lib/Roundcube/bootstrap.php
+++ b/program/lib/Roundcube/bootstrap.php
@@ -104,19 +104,29 @@ if (class_exists('PEAR')) {
 
 
 /**
- * Similar function as in_array() but case-insensitive
+ * Similar function as in_array() but case-insensitive with multibyte support.
  *
- * @param string $needle    Needle value
- * @param array  $heystack  Array to search in
+ * @param string $needle   Needle value
+ * @param array  $heystack Array to search in
  *
  * @return boolean True if found, False if not
  */
 function in_array_nocase($needle, $haystack)
 {
-    $needle = mb_strtolower($needle);
-    foreach ((array)$haystack as $value) {
-        if ($needle === mb_strtolower($value)) {
-            return true;
+    // use much faster method for ascii
+    if (is_ascii($needle)) {
+        foreach ((array) $haystack as $value) {
+            if (strcasecmp($value, $needle) === 0) {
+                return true;
+            }
+        }
+    }
+    else {
+        $needle = mb_strtolower($needle);
+        foreach ((array) $haystack as $value) {
+            if ($needle === mb_strtolower($value)) {
+                return true;
+            }
         }
     }
 
diff --git a/program/lib/Roundcube/rcube_imap.php b/program/lib/Roundcube/rcube_imap.php
index 1421563e4..672539417 100644
--- a/program/lib/Roundcube/rcube_imap.php
+++ b/program/lib/Roundcube/rcube_imap.php
@@ -2826,7 +2826,7 @@ class rcube_imap extends rcube_storage
             if (is_array($a_folders) && $name == '*' && !empty($this->conn->data['LIST'])) {
                 foreach ($a_folders as $idx => $folder) {
                     if (($opts = $this->conn->data['LIST'][$folder])
-                        && in_array('\\NonExistent', $opts)
+                        && in_array_nocase('\\NonExistent', $opts)
                     ) {
                         $this->conn->unsubscribe($folder);
                         unset($a_folders[$idx]);
@@ -3349,7 +3349,7 @@ class rcube_imap extends rcube_storage
         if ($subscription) {
             // It's possible we already called LIST command, check LIST data
             if (!empty($this->conn->data['LIST']) && !empty($this->conn->data['LIST'][$folder])
-                && in_array('\\Subscribed', $this->conn->data['LIST'][$folder])
+                && in_array_nocase('\\Subscribed', $this->conn->data['LIST'][$folder])
             ) {
                 $a_folders = array($folder);
             }