diff --git a/WORKSPACE b/WORKSPACE
index 6a673b2b61b..e158610bf8a 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -39,10 +39,10 @@ apple_support_dependencies()
 
 http_archive(
     name = "capnp-cpp",
-    integrity = "sha256-kVnOrg/h0eq37kBsFEHTUZax20JTR4/1eDy+kRY7wD8=",
-    strip_prefix = "capnproto-capnproto-bafc222/c++",
+    integrity = "sha256-eLxPfuuwuX9FTYCHgB8Q6tpBq/aVHzBbi8yie8WwpAo",
+    strip_prefix = "capnproto-capnproto-af4c99d/c++",
     type = "tgz",
-    urls = ["https://github.com/capnproto/capnproto/tarball/bafc222f2e602f18d126322deba159e68fddb42e"],
+    urls = ["https://github.com/capnproto/capnproto/tarball/af4c99d89dea3e6e299c3ff953ee03326fce80d6"],
 )
 
 http_archive(
diff --git a/src/workerd/io/worker-interface.c++ b/src/workerd/io/worker-interface.c++
index 328d7f269fc..e5dec1f9517 100644
--- a/src/workerd/io/worker-interface.c++
+++ b/src/workerd/io/worker-interface.c++
@@ -160,6 +160,10 @@ public:
     return wrap<void>(other.pumpTo(getInner()));
   }
 
+  kj::Maybe<kj::String> getPreferredExtensions(ExtensionsContext ctx) override {
+    return getInner().getPreferredExtensions(ctx);
+  };
+
   uint64_t sentByteCount() override { return 0; }
   uint64_t receivedByteCount() override { return 0; }
 
diff --git a/src/workerd/util/abortable.h b/src/workerd/util/abortable.h
index 2bef9b916b4..202c041348e 100644
--- a/src/workerd/util/abortable.h
+++ b/src/workerd/util/abortable.h
@@ -134,6 +134,11 @@ class AbortableWebSocket final: public kj::WebSocket,
     return impl.getInner().receivedByteCount();
   }
 
+  kj::Maybe<kj::String> getPreferredExtensions(ExtensionsContext ctx) override {
+    return impl.getInner().getPreferredExtensions(ctx);
+  };
+
+
 private:
   AbortableImpl<kj::WebSocket> impl;
 };