diff --git a/src/dawn/dawn.json b/src/dawn/dawn.json
index a68e7f9..cd838b2 100644
--- a/src/dawn/dawn.json
+++ b/src/dawn/dawn.json
@@ -2311,6 +2311,7 @@
     },
     "image copy buffer": {
         "category": "structure",
+        "extensible": "in",
         "members": [
             {"name": "layout", "type": "texture data layout"},
             {"name": "buffer", "type": "buffer"}
@@ -2318,6 +2319,7 @@
     },
     "image copy texture": {
         "category": "structure",
+        "extensible": "in",
         "members": [
             {"name": "texture", "type": "texture"},
             {"name": "mip level", "type": "uint32_t", "default": "0"},