diff --git a/src/set-cookie/parse.ts b/src/set-cookie/parse.ts
index 224ce5f..31451d5 100644
--- a/src/set-cookie/parse.ts
+++ b/src/set-cookie/parse.ts
@@ -57,7 +57,7 @@ export function parseSetCookie(
         break;
       }
       case "samesite": {
-        cookie.sameSite = partValue;
+        cookie.sameSite = partValue as SetCookie["sameSite"];
         break;
       }
       default: {
diff --git a/src/set-cookie/types.ts b/src/set-cookie/types.ts
index 134af60..965389c 100644
--- a/src/set-cookie/types.ts
+++ b/src/set-cookie/types.ts
@@ -56,7 +56,7 @@ export interface SetCookie {
   /**
    * Indicates a cookie ought not to be sent along with cross-site requests
    */
-  sameSite?: string | undefined;
+  sameSite?: true | false | "lax" | "strict" | "none" | undefined;
 
   [key: string]: unknown;
 }