diff --git a/packages/apollo-schemas/src/assembly.schema.ts b/packages/apollo-schemas/src/assembly.schema.ts
index 4a4693d8..728d8d8b 100644
--- a/packages/apollo-schemas/src/assembly.schema.ts
+++ b/packages/apollo-schemas/src/assembly.schema.ts
@@ -1,6 +1,8 @@
 import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose'
 import { Schema as MongooseSchema, Types } from 'mongoose'
 
+import { File } from './file.schema'
+
 export type AssemblyDocument = Assembly & Document
 
 @Schema()
@@ -26,14 +28,20 @@ export class Assembly {
   @Prop({ type: { fa: String, fai: String, gzi: String } })
   externalLocation: { fa: string; fai: string; gzi?: string }
 
-  @Prop({ type: { fa: String, fai: String, gzi: String } })
-  fileIds: { fa: string; fai: string; gzi?: string } // Store fileId of fa/fai/gzi.
+  @Prop({
+    type: {
+      fa: { type: MongooseSchema.Types.ObjectId, ref: 'File' },
+      fai: { type: MongooseSchema.Types.ObjectId, ref: 'File' },
+      gzi: { type: MongooseSchema.Types.ObjectId, ref: 'File' },
+    },
+  })
+  fileIds: { fa: string; fai: string; gzi: string } // Store fileId of fa/fai/gzi.
 
   @Prop({ type: [{ type: MongooseSchema.Types.ObjectId, ref: 'Check' }] })
   checks: Types.ObjectId[]
 
-  @Prop()
-  fileId: string
+  @Prop({ type: MongooseSchema.Types.ObjectId, ref: 'File' })
+  file: File
 }
 
 export const AssemblySchema = SchemaFactory.createForClass(Assembly)