diff --git a/app/build.gradle b/app/build.gradle
index 52953b0..6530752 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -203,8 +203,8 @@ dependencies {
     implementation 'com.squareup.okhttp3:okhttp-tls:4.9.0'
     implementation 'com.squareup.okhttp3:logging-interceptor:3.8.1'
 
-    googleApiImplementation "com.android.billingclient:billing:3.0.3"
-    googleApiImplementation "com.android.billingclient:billing-ktx:3.0.3"
+    googleApiImplementation "com.android.billingclient:billing:4.0.0"
+    googleApiImplementation "com.android.billingclient:billing-ktx:4.0.0"
 
     implementation('io.socket:socket.io-client:1.0.0') {
         exclude group: 'org.json', module: 'json'
diff --git a/app/src/main/java/io/timelimit/android/ui/payment/ActivityPurchaseModel.kt b/app/src/main/java/io/timelimit/android/ui/payment/ActivityPurchaseModel.kt
index b3effd2..c6c64eb 100644
--- a/app/src/main/java/io/timelimit/android/ui/payment/ActivityPurchaseModel.kt
+++ b/app/src/main/java/io/timelimit/android/ui/payment/ActivityPurchaseModel.kt
@@ -137,11 +137,11 @@ class ActivityPurchaseModel(application: Application): AndroidViewModel(applicat
     }
 
     suspend fun queryPurchases() = initAndUseClient { client ->
-        val response = client.queryPurchases(BillingClient.SkuType.INAPP)
+        val response = client.queryPurchasesAsync(BillingClient.SkuType.INAPP)
 
         response.billingResult.assertSuccess()
 
-        response.purchasesList!!.filter {
+        response.purchasesList.filter {
             it.purchaseState == Purchase.PurchaseState.PURCHASED
         }
     }
@@ -151,11 +151,11 @@ class ActivityPurchaseModel(application: Application): AndroidViewModel(applicat
             isWorkingInternal.setTemporarily(true).use {
                 try {
                     initAndUseClient { client ->
-                        val result = client.queryPurchases(BillingClient.SkuType.INAPP)
+                        val result = client.queryPurchasesAsync(BillingClient.SkuType.INAPP)
 
                         result.billingResult.assertSuccess()
 
-                        for (purchase in result.purchasesList!!) {
+                        for (purchase in result.purchasesList) {
                             handlePurchase(purchase, client)
                         }
                     }
@@ -219,7 +219,9 @@ class ActivityPurchaseModel(application: Application): AndroidViewModel(applicat
             Log.d(LOG_TAG, "handlePurchase($purchase)")
         }
 
-        if (PurchaseIds.SAL_SKUS.contains(purchase.sku)) {
+        val sku = purchase.skus.single()
+
+        if (PurchaseIds.SAL_SKUS.contains(sku)) {
             // just acknowledge
 
             billingClient.acknowledgePurchase(
@@ -227,7 +229,7 @@ class ActivityPurchaseModel(application: Application): AndroidViewModel(applicat
                             .setPurchaseToken(purchase.purchaseToken)
                             .build()
             ).assertSuccess()
-        } else if (PurchaseIds.BUY_SKUS.contains(purchase.sku)) {
+        } else if (PurchaseIds.BUY_SKUS.contains(sku)) {
             // send and consume
 
             val server = logic.serverLogic.getServerConfigCoroutine()
@@ -251,7 +253,7 @@ class ActivityPurchaseModel(application: Application): AndroidViewModel(applicat
             }
         } else {
             if (BuildConfig.DEBUG) {
-                Log.d(LOG_TAG, "don't know how to handle ${purchase.sku}")
+                Log.d(LOG_TAG, "don't know how to handle $sku")
             }
         }
     }
diff --git a/app/src/main/java/io/timelimit/android/ui/payment/StayAwesomeModel.kt b/app/src/main/java/io/timelimit/android/ui/payment/StayAwesomeModel.kt
index 754db3f..3cb2396 100644
--- a/app/src/main/java/io/timelimit/android/ui/payment/StayAwesomeModel.kt
+++ b/app/src/main/java/io/timelimit/android/ui/payment/StayAwesomeModel.kt
@@ -48,7 +48,7 @@ class StayAwesomeModel(application: Application): AndroidViewModel(application)
                                     id = skuId,
                                     title = sku?.description ?: skuId,
                                     price = sku?.price ?: "???",
-                                    bought = purchases.find { it.sku == skuId } != null
+                                    bought = purchases.find { purchase -> purchase.skus.find { sku -> sku == skuId } != null } != null
                             )
                         }
                 )
diff --git a/app/src/noGoogleApi/java/com/android/billingclient/api/Mocks.kt b/app/src/noGoogleApi/java/com/android/billingclient/api/Mocks.kt
index 35465a7..aba32d8 100644
--- a/app/src/noGoogleApi/java/com/android/billingclient/api/Mocks.kt
+++ b/app/src/noGoogleApi/java/com/android/billingclient/api/Mocks.kt
@@ -32,7 +32,7 @@ object BillingClient {
     fun launchBillingFlow(activity: Activity, params: BillingFlowParams) = BillingResult
     fun acknowledgePurchase(params: AcknowledgePurchaseParams) = BillingResult
     fun consumePurchase(params: ConsumeParams) = BillingResult
-    fun queryPurchases(type: String) = QueryPurchasesResult
+    suspend fun queryPurchasesAsync(type: String) = QueryPurchasesResult
 
     object BillingResponseCode {
         const val OK = 0
@@ -74,7 +74,7 @@ object SkuDetailsParams {
 object Purchase {
     const val purchaseState = PurchaseState.PURCHASED
     const val isAcknowledged = true
-    const val sku = ""
+    val skus = listOf("")
     const val purchaseToken = ""
     const val originalJson = ""
     const val signature = ""
@@ -113,7 +113,7 @@ object BillingFlowParams {
 
 object QueryPurchasesResult {
     val billingResult = BillingResult
-    val purchasesList: List<Purchase>? = emptyList()
+    val purchasesList: List<Purchase> = emptyList()
 }
 
 data class QuerySkuDetailsResult(val billingResult: BillingResult, val details: List<SkuDetails>?) {