diff --git a/inputfiles/addedTypes.jsonc b/inputfiles/addedTypes.jsonc
index 64861d798..b69899a60 100644
--- a/inputfiles/addedTypes.jsonc
+++ b/inputfiles/addedTypes.jsonc
@@ -425,19 +425,6 @@
                 "legacyNamespace": "WebAssembly",
                 "overrideType": "Function | Global | Memory | Table"
             },
-            {
-                "name": "Exports",
-                "legacyNamespace": "WebAssembly",
-                "type": "record",
-                "subtype": [
-                    {
-                        "type": "DOMString"
-                    },
-                    {
-                        "type": "ExportValue"
-                    }
-                ]
-            },
             {
                 "name": "ModuleImports",
                 "legacyNamespace": "WebAssembly",
diff --git a/inputfiles/patches/wasm-js-api.kdl b/inputfiles/patches/wasm-js-api.kdl
new file mode 100644
index 000000000..8ec4446c7
--- /dev/null
+++ b/inputfiles/patches/wasm-js-api.kdl
@@ -0,0 +1,6 @@
+typedef Exports legacyNamespace=WebAssembly {
+  type record union=#true {
+    type DOMString
+    type ExportValue
+  }
+}
diff --git a/src/build/patches.ts b/src/build/patches.ts
index ac72d1742..50e15d318 100644
--- a/src/build/patches.ts
+++ b/src/build/patches.ts
@@ -59,11 +59,14 @@ function handleSingleTypeNode(type: Node): DeepPartial<Typed> {
   if (!isTyped) {
     throw new Error("Expected a type node");
   }
+  const typeValue = type.values[0];
   const subType =
     type.children.length > 0 ? handleTyped(type.children) : undefined;
+  const isUnion = typeof type.properties.union == "boolean";
   return {
-    ...optionalMember("type", "string", type.values[0]),
-    subtype: subType,
+    ...optionalMember("type", "string", typeValue),
+    subtype:
+      isUnion && typeof subType?.type !== "string" ? subType?.type : subType,
     ...optionalMember("nullable", "boolean", type.properties?.nullable),
   };
 }