diff --git a/types/sequelize/index.d.ts b/types/sequelize/index.d.ts
index 3c089fd841..c5974a56d2 100644
--- a/types/sequelize/index.d.ts
+++ b/types/sequelize/index.d.ts
@@ -4792,6 +4792,11 @@ declare namespace sequelize {
          */
         operator?: string;
 
+        /**
+         * Condition for partioal index
+         */
+        where?: WhereOptions;
+
     }
 
     /**
diff --git a/types/sequelize/sequelize-tests.ts b/types/sequelize/sequelize-tests.ts
index 4e1bb513b1..a7dde618af 100644
--- a/types/sequelize/sequelize-tests.ts
+++ b/types/sequelize/sequelize-tests.ts
@@ -1290,7 +1290,10 @@ s.define( 'UserWithUniqueUsername', {
             name : 'user_and_email_index',
             unique : true,
             method : 'BTREE',
-            fields : ['user_id', { attribute : 'email', collate : 'en_US', order : 'DESC', length : 5 }]
+            fields : ['user_id', { attribute : 'email', collate : 'en_US', order : 'DESC', length : 5 }],
+            where : {
+                user_id : { $not: null }
+            }
         },
         {
             fields: ['data'],