diff --git a/types/knex/index.d.ts b/types/knex/index.d.ts
index fe8d46658a..c1fb224fa0 100644
--- a/types/knex/index.d.ts
+++ b/types/knex/index.d.ts
@@ -312,9 +312,9 @@ declare namespace Knex {
     }
 
     interface Union {
-        (callback: QueryCallback, wrap?: boolean): QueryBuilder;
-        (callbacks: QueryCallback[], wrap?: boolean): QueryBuilder;
-        (...callbacks: QueryCallback[]): QueryBuilder;
+        (callback: QueryCallback | QueryBuilder | Raw, wrap?: boolean): QueryBuilder;
+        (callbacks: (QueryCallback | QueryBuilder | Raw)[], wrap?: boolean): QueryBuilder;
+        (...callbacks: (QueryCallback | QueryBuilder | Raw)[]): QueryBuilder;
         // (...callbacks: QueryCallback[], wrap?: boolean): QueryInterface;
     }
 
diff --git a/types/knex/knex-tests.ts b/types/knex/knex-tests.ts
index 329ed9d414..0037948415 100644
--- a/types/knex/knex-tests.ts
+++ b/types/knex/knex-tests.ts
@@ -1145,3 +1145,19 @@ knex('characters')
     .whereIn(['name', 'class'], function() {
         this.select('name', 'class').from('characters');
     });
+
+knex('characters')
+    .select()
+    .where({ name: 'Bar', class: 'Fighter' })
+    .union(knex('characters').select().where({ name: 'Foo', class: 'Druid' }));
+knex('characters')
+    .select()
+    .where({ name: 'Bar', class: 'Fighter' })
+    .union([knex('characters').select().where({ name: 'Foo', class: 'Druid' })]);
+knex('characters')
+    .select()
+    .where({ name: 'Bar', class: 'Fighter' })
+    .union(
+        knex('characters').select().where({ name: 'Foo', class: 'Druid' }),
+        knex('characters').select().where({ name: 'Baz', class: 'Paladin' })
+    );