diff --git a/index.src.html b/index.src.html
index 1077479f..c16f2faa 100644
--- a/index.src.html
+++ b/index.src.html
@@ -1167,7 +1167,7 @@
   undefined reset();
   undefined close();
 
-  static Promise<boolean> isConfigSupported(VideoEncoderConfig config);
+  static Promise<VideoEncoderSupport> isConfigSupported(VideoEncoderConfig config);
 };
 
 dictionary VideoEncoderInit {