diff --git a/wp-admin/includes/class-wp-filesystem-direct.php b/wp-admin/includes/class-wp-filesystem-direct.php
index d73b715bb2..ebd64b3e82 100644
--- a/wp-admin/includes/class-wp-filesystem-direct.php
+++ b/wp-admin/includes/class-wp-filesystem-direct.php
@@ -287,7 +287,7 @@ class WP_Filesystem_Direct extends WP_Filesystem_Base {
 		// safe mode fails with a trailing slash under certain PHP versions.
 		$path = untrailingslashit($path);
 		if ( empty($path) )
-			$path = '/';
+			return false;
 
 		if ( ! $chmod )
 			$chmod = FS_CHMOD_DIR;
diff --git a/wp-admin/includes/class-wp-filesystem-ftpext.php b/wp-admin/includes/class-wp-filesystem-ftpext.php
index 5967c6df64..79bacfbaa4 100644
--- a/wp-admin/includes/class-wp-filesystem-ftpext.php
+++ b/wp-admin/includes/class-wp-filesystem-ftpext.php
@@ -247,6 +247,10 @@ class WP_Filesystem_FTPext extends WP_Filesystem_Base {
 		return false;
 	}
 	function mkdir($path, $chmod = false, $chown = false, $chgrp = false) {
+		$path = untrailingslashit($path);
+		if ( empty($path) )
+			return false;
+
 		if ( !@ftp_mkdir($this->link, $path) )
 			return false;
 		$this->chmod($path, $chmod);
diff --git a/wp-admin/includes/class-wp-filesystem-ftpsockets.php b/wp-admin/includes/class-wp-filesystem-ftpsockets.php
index 1dc170a93c..7dae3b7737 100644
--- a/wp-admin/includes/class-wp-filesystem-ftpsockets.php
+++ b/wp-admin/includes/class-wp-filesystem-ftpsockets.php
@@ -267,6 +267,10 @@ class WP_Filesystem_ftpsockets extends WP_Filesystem_Base {
 	}
 
 	function mkdir($path, $chmod = false, $chown = false, $chgrp = false ) {
+		$path = untrailingslashit($path);
+		if ( empty($path) )
+			return false;
+
 		if ( ! $this->ftp->mkdir($path) )
 			return false;
 		if ( ! $chmod )
diff --git a/wp-admin/includes/class-wp-filesystem-ssh2.php b/wp-admin/includes/class-wp-filesystem-ssh2.php
index 0e656ff294..3114456e09 100644
--- a/wp-admin/includes/class-wp-filesystem-ssh2.php
+++ b/wp-admin/includes/class-wp-filesystem-ssh2.php
@@ -311,6 +311,9 @@ class WP_Filesystem_SSH2 extends WP_Filesystem_Base {
 
 	function mkdir($path, $chmod = false, $chown = false, $chgrp = false) {
 		$path = untrailingslashit($path);
+		if ( empty($path) )
+			return false;
+
 		if ( ! $chmod )
 			$chmod = FS_CHMOD_DIR;
 		if ( ! ssh2_sftp_mkdir($this->sftp_link, $path, $chmod, true) )