diff --git a/types/expressions.d.ts b/types/expressions.d.ts
index 10ee0bf1559..988b0357568 100644
--- a/types/expressions.d.ts
+++ b/types/expressions.d.ts
@@ -2448,7 +2448,8 @@ declare module 'mongoose' {
     BinaryExpression |
     FunctionExpression |
     ObjectIdExpression |
-    ConditionalExpressionOperator;
+    ConditionalExpressionOperator |
+    Expression.Let;
 
   export type ObjectIdExpression =
     TypeExpressionOperatorReturningObjectId;