diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index 1c675a6e..f02a321a 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -500,7 +500,7 @@ class SFTP extends SSH2
             8 => 'NET_SFTP_TYPE_BLOCK_DEVICE',
             9 => 'NET_SFTP_TYPE_FIFO'
         ];
-        $this->define_array(
+        self::define_array(
             $this->packet_types,
             $this->status_codes,
             $this->attributes,
diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index f680a3b3..91af6098 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -1157,7 +1157,7 @@ class SSH2
             1 => 'NET_SSH2_EXTENDED_DATA_STDERR'
         ];
 
-        $this->define_array(
+        self::define_array(
             $this->message_numbers,
             $this->disconnect_reasons,
             $this->channel_open_failure_reasons,
@@ -4506,7 +4506,7 @@ class SSH2
      * @param mixed[] ...$args
      * @access protected
      */
-    protected function define_array(...$args)
+    protected static function define_array(...$args)
     {
         foreach ($args as $arg) {
             foreach ($arg as $key => $value) {