diff --git a/admin/create-theme/cbt-zip-archive.php b/admin/create-theme/cbt-zip-archive.php
index 4862fc9d..3799192c 100644
--- a/admin/create-theme/cbt-zip-archive.php
+++ b/admin/create-theme/cbt-zip-archive.php
@@ -8,21 +8,24 @@ class CbtZipArchive extends ZipArchive {
 		private string $theme_slug;
 
 		function __construct( $theme_slug ) {
-			$this->theme_slug = $theme_slug;
+			// If the original theme is in a subfolder the theme slug will be the last part of the path
+			$complete_slug      = explode( DIRECTORY_SEPARATOR, $theme_slug );
+			$folder             = end( $complete_slug );
+			$this->theme_folder = $folder;
 		}
 
 		function addFromStringToTheme( $name, $content ) {
-			$name = $this->theme_slug . '/' . $name;
+			$name = $this->theme_folder . '/' . $name;
 			return parent::addFromString( $name, $content );
 		}
 
 		function addFileToTheme( $filepath, $entryname ) {
-			$entryname = $this->theme_slug . '/' . $entryname;
+			$entryname = $this->theme_folder . '/' . $entryname;
 			return parent::addFile( $filepath, $entryname );
 		}
 
 		function addThemeDir( $dirname ) {
-			$dirname = $this->theme_slug . '/' . $dirname;
+			$dirname = $this->theme_folder . '/' . $dirname;
 			return parent::addEmptyDir( $dirname );
 		}