diff --git a/pdf.php b/pdf.php
index ac5987bd9..69a291969 100644
--- a/pdf.php
+++ b/pdf.php
@@ -41,7 +41,11 @@
 define( 'PDF_PLUGIN_URL', plugin_dir_url( __FILE__ ) ); /* plugin directory url */
 define( 'PDF_PLUGIN_BASENAME', plugin_basename( __FILE__ ) ); /* the plugin basename */
 define( 'GPDF_PLUGIN_FILE', __FILE__ );
-define( 'GPDF_API_URL', 'https://api.gravitypdf.com' );
+
+/* Allow wp-config.php to point licensing/update requests at a staging endpoint */
+if ( ! defined( 'GPDF_API_URL' ) ) {
+	define( 'GPDF_API_URL', 'https://api.gravitypdf.com' );
+}
 
 if ( ! class_exists( 'GFPDF_Major_Compatibility_Checks' ) ) {
 	/*
diff --git a/src/Model/Model_Settings.php b/src/Model/Model_Settings.php
index 7501b5ada..c8919b168 100644
--- a/src/Model/Model_Settings.php
+++ b/src/Model/Model_Settings.php
@@ -443,6 +443,12 @@ function ( $addon ) {
 			)
 		);
 
+		/*
+		 * Keep $bulk_api_params numerically indexed. The API keys its response array by the same
+		 * keys it receives, so numeric indices make it return a JSON array (which the response
+		 * handlers below decode via is_array()). Switching to slug keys would return a JSON object
+		 * and silently break bulk handling.
+		 */
 		$bulk_api_params = [];
 		foreach ( $products as $product ) {
 			/* skip improperly-registered plugins */