diff --git a/lib/class-wp-theme-json-resolver-gutenberg.php b/lib/class-wp-theme-json-resolver-gutenberg.php
index 950d9e00e6243f..189d411db2257f 100644
--- a/lib/class-wp-theme-json-resolver-gutenberg.php
+++ b/lib/class-wp-theme-json-resolver-gutenberg.php
@@ -322,9 +322,6 @@ public static function get_theme_data( $deprecated = array(), $options = array()
 			}
 			$theme_support_data['settings']['color']['defaultGradients'] = $default_gradients;
 
-			// Classic themes without a theme.json don't support global duotone.
-			$theme_support_data['settings']['color']['defaultDuotone'] = false;
-
 			// Allow themes to enable all border settings via theme_support.
 			if ( current_theme_supports( 'border' ) ) {
 				$theme_support_data['settings']['border']['color']  = true;