diff --git a/php/generate-html.php b/php/generate-html.php
index b942f8b..d6bfb73 100644
--- a/php/generate-html.php
+++ b/php/generate-html.php
@@ -26,8 +26,8 @@
 		// This works? Yes, yes it does.
 		// We do this to isolate the environment and include-once triggers,
 		// otherwise we could include the documents in an ob_* wrapper.
-		$document = `php $phppath`;
+		$document = `php $phppath`; // should be identical to shell_exec("php $phppath")
 		
 		file_put_contents($docpath, $document);
 	}
-?>
\ No newline at end of file
+?>
diff --git a/sites/+components/qr_modals.php b/sites/+components/qr_modals.php
index dab4575..909d0cf 100644
--- a/sites/+components/qr_modals.php
+++ b/sites/+components/qr_modals.php
@@ -12,7 +12,9 @@
 		// https://developers.google.com/chart/infographics/docs/qr_codes
 		$png_cached = room_qr_code_cached($room_id);
 		if (file_exists($png_cached)) 
+//			fwrite(STDERR, "QR code found for " . $room_id . PHP_EOL);
 			return base64_encode(file_get_contents($png_cached));
+//			fwrite(STDERR, "QR code NOT found for " . $room_id . PHP_EOL);
 		$data = urlencode($join_url);
 		$api_url =
 			"https://chart.googleapis.com/chart?cht=qr" .