diff --git a/src/transports/imap/imap_transport.php b/src/transports/imap/imap_transport.php
index b71dce97..38ea3346 100644
--- a/src/transports/imap/imap_transport.php
+++ b/src/transports/imap/imap_transport.php
@@ -1089,7 +1089,7 @@ public function fetchSizes( $messages )
         }
 
         $sizes = array();
-        $ids = implode( $messages, ',' );
+        $ids = implode( ',', $messages );
 
         $tag = $this->getNextTag();
         $this->connection->sendData( "{$tag} {$uid}FETCH {$ids} (RFC822.SIZE)" );
@@ -2035,7 +2035,7 @@ public function fetchFlags( $messages )
         }
 
         $flags = array();
-        $ids = implode( $messages, ',' );
+        $ids = implode( ',', $messages );
 
         $tag = $this->getNextTag();
         $this->connection->sendData( "{$tag} {$uid}FETCH {$ids} (FLAGS)" );