diff --git a/CHANGELOG b/CHANGELOG
index 4cff69da85d..370ce7cacb1 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -3,6 +3,7 @@ CHANGELOG Roundcube Webmail
 
 - Managesieve: Fix handling of scripts with nested rules (#5540)
 - Fix variable substitution in ldap host for some use-cases, e.g. new_user_identity (#5544)
+- Enigma: Fix PHP fatal error when decrypting a message with invalid signature (#5555)
 
 RELEASE 1.2.3
 -------------
diff --git a/plugins/enigma/lib/enigma_driver_gnupg.php b/plugins/enigma/lib/enigma_driver_gnupg.php
index 07ca0032274..afa54ed2ea6 100644
--- a/plugins/enigma/lib/enigma_driver_gnupg.php
+++ b/plugins/enigma/lib/enigma_driver_gnupg.php
@@ -409,17 +409,20 @@ protected function get_error_from_exception($e)
      */
     protected function parse_signature($sig)
     {
-        $user = $sig->getUserId();
-
         $data = new enigma_signature();
+
         $data->id          = $sig->getId();
         $data->valid       = $sig->isValid();
         $data->fingerprint = $sig->getKeyFingerprint();
         $data->created     = $sig->getCreationDate();
         $data->expires     = $sig->getExpirationDate();
-        $data->name        = $user->getName();
-        $data->comment     = $user->getComment();
-        $data->email       = $user->getEmail();
+
+        // In case of ERRSIG user may not be set
+        if ($user = $sig->getUserId()) {
+            $data->name    = $user->getName();
+            $data->comment = $user->getComment();
+            $data->email   = $user->getEmail();
+        }
 
         return $data;
     }