diff --git a/src/polymorphic.repository.ts b/src/polymorphic.repository.ts
index 89b2555..94884ea 100644
--- a/src/polymorphic.repository.ts
+++ b/src/polymorphic.repository.ts
@@ -38,10 +38,10 @@ const PrimaryColumn = (options: PolymorphicMetadataInterface): string =>
 export abstract class AbstractPolymorphicRepository<
   E extends ObjectLiteral,
 > extends Repository<E> {
-  public static createRepository(
-    ds: DataSource,
-    repository: new (...args: any[]) => any,
-  ) {
+  public static createRepository<
+    E extends ObjectLiteral,
+    R extends AbstractPolymorphicRepository<E>,
+  >(ds: DataSource, repository: new (...args: any[]) => R) {
     const entity = Reflect.getMetadata(POLYMORPHIC_REPOSITORY, repository);
     const baseRepository = ds.getRepository<any>(entity);
     return new repository(