diff --git a/types/tedious/index.d.ts b/types/tedious/index.d.ts
index 39d8664e0d..b89ac58beb 100644
--- a/types/tedious/index.d.ts
+++ b/types/tedious/index.d.ts
@@ -297,7 +297,7 @@ export interface ConnectionConfig {
 
 export interface ParameterOptions {
     //  for VarChar, NVarChar, VarBinary
-    length?: number;
+    length?: number | 'max';
     // precision for Numeric, Decimal
     precision?: number;
     // scale for Numeric, Decimal, Time, DateTime2, DateTimeOffset