diff --git a/Makefile b/Makefile
index f6fcf899d..a0b49fe91 100644
--- a/Makefile
+++ b/Makefile
@@ -35,7 +35,7 @@ PROTO_PATHS = paths=source_relative:$(PROTO_OUT)
 OAPI_OUT := openapi
 OAPI3_PATH := .components.schemas.Payload
 
-NEX_GEN ?= nex-gen
+NEX_GEN ?= nexgen
 
 $(PROTO_OUT):
 	mkdir $(PROTO_OUT)
@@ -144,20 +144,29 @@ nexus-rpc-yaml-install:
 ##### Compile system Nexus WIT files #####
 system-nexus-wit: system-nexus-wit-install nex-gen-install
 	printf $(COLOR) "Generate system Nexus WIT..."
-	protoc -I $(PROTO_ROOT) \
+	tmp=$$(mktemp -d); trap 'rm -rf "$$tmp"' EXIT; \
+	protoc -I $(PROTO_ROOT) --include_imports \
+		--descriptor_set_out="$$tmp/system.bin" \
 		--system-nexus-wit_opt=output=nexus/workflow-service.wit \
 		--system-nexus-wit_opt=nex_gen=$(NEX_GEN) \
 		--system-nexus-wit_opt=linked_input=nexus/deps \
 		--system-nexus-wit_out=. \
-		temporal/api/workflowservice/v1/service.proto
+		temporal/api/workflowservice/v1/service.proto \
+		temporal/api/notificationservice/v1/request_response.proto && \
+	$(NEX_GEN) add-message \
+		--descriptors "$$tmp/system.bin" \
+		--file temporal/api/notificationservice/v1/request_response.proto \
+		--input nexus/notification-service.wit \
+		--input nexus/deps \
+		--output nexus/notification-service.wit
 
 system-nexus-wit-install:
 	printf $(COLOR) "Build and install protoc-gen-system-nexus-wit..."
 	@cd cmd/protoc-gen-system-nexus-wit && go install .
 
 nex-gen-install:
-	printf $(COLOR) "Install nex-gen if missing..."
-	command -v $(NEX_GEN) >/dev/null || cargo install nex-gen --version ^0.1
+	printf $(COLOR) "Install nexgen if missing..."
+	command -v $(NEX_GEN) >/dev/null || cargo install nexgen --version ^0.2 --features advanced
 
 ##### Clean #####
 clean:
diff --git a/nexus/notification-service.wit b/nexus/notification-service.wit
new file mode 100644
index 000000000..19a89381c
--- /dev/null
+++ b/nexus/notification-service.wit
@@ -0,0 +1,34 @@
+package temporal:nexus@1.0.0;
+
+world system {
+  export notification-service;
+}
+
+interface notification-service {
+  use nexus:temporal-types/model@1.0.0.{
+    failure,
+    placeholder,
+  };
+
+  /// @nexus.type-parameter
+  type source-context-t = placeholder;
+
+  /// @nexus.type-parameter
+  type output-t = placeholder;
+
+  /// @nexus.proto "temporal.api.notificationservice.v1.OnCompleteRequest.result"
+  variant on-complete-request-result {
+    success(output-t),
+    failure(failure),
+  }
+
+  /// @nexus.proto "temporal.api.notificationservice.v1.OnCompleteRequest"
+  record on-complete-request {
+    %result: on-complete-request-result,
+    source-context: source-context-t,
+  }
+
+  /// @nexus.proto "temporal.api.notificationservice.v1.OnCompleteResponse"
+  record on-complete-response {
+  }
+}
\ No newline at end of file