diff --git a/packages/apollo-server-core/src/types.ts b/packages/apollo-server-core/src/types.ts
index d0c391437da..bf11de82f62 100644
--- a/packages/apollo-server-core/src/types.ts
+++ b/packages/apollo-server-core/src/types.ts
@@ -68,7 +68,7 @@ type BaseConfig = Pick<
 // fields that are not specific to a single integration
 export interface Config extends BaseConfig {
   modules?: GraphQLSchemaModule[];
-  typeDefs?: DocumentNode | Array<DocumentNode>;
+  typeDefs?: DocumentNode | Array<DocumentNode> | string | Array<string>;
   parseOptions?: GraphQLParseOptions;
   resolvers?: IResolvers;
   schema?: GraphQLSchema;