diff --git a/dawn.json b/dawn.json
index 3886240..c6d231d 100644
--- a/dawn.json
+++ b/dawn.json
@@ -1162,7 +1162,8 @@
             {"name": "label", "type": "char", "annotation": "const*", "length": "strlen", "optional": true},
             {"name": "color attachment count", "type": "uint32_t"},
             {"name": "color attachments", "type": "render pass color attachment descriptor", "annotation": "const*", "length": "color attachment count"},
-            {"name": "depth stencil attachment", "type": "render pass depth stencil attachment descriptor", "annotation": "const*", "optional": true}
+            {"name": "depth stencil attachment", "type": "render pass depth stencil attachment descriptor", "annotation": "const*", "optional": true},
+            {"name": "occlusion query set", "type": "query set", "optional": true}
         ]
     },
     "render pass encoder": {
diff --git a/src/dawn_native/CommandEncoder.cpp b/src/dawn_native/CommandEncoder.cpp
index e8a6b46..01a5b62 100644
--- a/src/dawn_native/CommandEncoder.cpp
+++ b/src/dawn_native/CommandEncoder.cpp
@@ -370,6 +370,10 @@
                     device, descriptor->depthStencilAttachment, width, height, sampleCount));
             }
 
+            if (descriptor->occlusionQuerySet != nullptr) {
+                return DAWN_VALIDATION_ERROR("occlusionQuerySet not implemented");
+            }
+
             if (descriptor->colorAttachmentCount == 0 &&
                 descriptor->depthStencilAttachment == nullptr) {
                 return DAWN_VALIDATION_ERROR("Cannot use render pass with no attachments.");
diff --git a/src/utils/WGPUHelpers.h b/src/utils/WGPUHelpers.h
index a01cee6..5c5f9f2 100644
--- a/src/utils/WGPUHelpers.h
+++ b/src/utils/WGPUHelpers.h
@@ -67,7 +67,7 @@
 
         std::array<wgpu::RenderPassColorAttachmentDescriptor, kMaxColorAttachments>
             cColorAttachments;
-        wgpu::RenderPassDepthStencilAttachmentDescriptor cDepthStencilAttachmentInfo;
+        wgpu::RenderPassDepthStencilAttachmentDescriptor cDepthStencilAttachmentInfo = {};
     };
 
     struct BasicRenderPass {