diff --git a/lib/class-wp-theme-json-gutenberg.php b/lib/class-wp-theme-json-gutenberg.php
index 764a1af8d774ae..4f6f7db7384d78 100644
--- a/lib/class-wp-theme-json-gutenberg.php
+++ b/lib/class-wp-theme-json-gutenberg.php
@@ -1073,7 +1073,6 @@ public function merge( $incoming ) {
 		// For leaf values that are arrays it will use the numeric indexes for replacement.
 		// In those cases, we want to replace the existing with the incoming value, if it exists.
 		$to_replace   = array();
-		$to_replace[] = array( 'custom' );
 		$to_replace[] = array( 'spacing', 'units' );
 		$to_replace[] = array( 'color', 'duotone' );
 		foreach ( self::VALID_ORIGINS as $origin ) {