diff --git a/src/controllers/04-service-controller.ts b/src/controllers/04-service-controller.ts
index 07abd4f..97eb696 100644
--- a/src/controllers/04-service-controller.ts
+++ b/src/controllers/04-service-controller.ts
@@ -277,6 +277,8 @@ export class ServiceController extends Controller {
   async createService(@Request() req: RequestWithUser, @Body() body: ServiceCreate) {
     const { work, productGroupId, ...payload } = body;
 
+    if (!payload.workflowId) payload.workflowId = undefined;
+
     const [productGroup] = await prisma.$transaction([
       prisma.productGroup.findFirst({
         include: {
@@ -380,6 +382,8 @@ export class ServiceController extends Controller {
 
     const { work, productGroupId, ...payload } = body;
 
+    if (!payload.workflowId && payload.workflowId !== undefined) payload.workflowId = undefined;
+
     const [productGroup] = await prisma.$transaction([
       prisma.productGroup.findFirst({
         include: {