diff --git a/dawn.json b/dawn.json
index 3a666eeb91..5470a27444 100644
--- a/dawn.json
+++ b/dawn.json
@@ -951,6 +951,7 @@
 
     "render pass descriptor": {
         "category": "structure",
+        "extensible": true,
         "members": [
             {"name": "label", "type": "char", "annotation": "const*", "length": "strlen", "optional": true},
             {"name": "color attachment count", "type": "uint32_t"},
diff --git a/examples/CHelloTriangle.cpp b/examples/CHelloTriangle.cpp
index b3928a9e18..f66f514c1d 100644
--- a/examples/CHelloTriangle.cpp
+++ b/examples/CHelloTriangle.cpp
@@ -129,6 +129,7 @@ void frame() {
     DawnTexture backbuffer = dawnSwapChainGetNextTexture(swapchain);
     DawnTextureView backbufferView = dawnTextureCreateView(backbuffer, nullptr);
     DawnRenderPassDescriptor renderpassInfo;
+    renderpassInfo.nextInChain = nullptr;
     renderpassInfo.label = nullptr;
     DawnRenderPassColorAttachmentDescriptor colorAttachment;
     {