diff --git a/src/stores/user.ts b/src/stores/user.ts
index e791c51..8e810db 100644
--- a/src/stores/user.ts
+++ b/src/stores/user.ts
@@ -278,7 +278,7 @@ export const sendUserData = async () => {
 export const addTariffToCart = async (tariffId: string) => {
   const [patchCartResponse, patchCartError] = await patchCart(tariffId);
 
-  if (patchCartError !== undefined) {
+  if (patchCartError === undefined) {
     setCart(patchCartResponse);
   }
   return({patchCartResponse, patchCartError})