diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt
index 39449c42..b5d34604 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/SzkolnyApi.kt
@@ -28,6 +28,7 @@ import pl.szczodrzynski.edziennik.data.db.entity.FeedbackMessage
 import pl.szczodrzynski.edziennik.data.db.entity.Notification
 import pl.szczodrzynski.edziennik.data.db.entity.Profile
 import pl.szczodrzynski.edziennik.data.db.full.EventFull
+import pl.szczodrzynski.edziennik.ext.keys
 import pl.szczodrzynski.edziennik.ext.md5
 import pl.szczodrzynski.edziennik.ext.toApiError
 import pl.szczodrzynski.edziennik.ext.toErrorCode
@@ -126,7 +127,10 @@ class SzkolnyApi(val app: App) : CoroutineScope {
      * or null if it's a HTTP call error.
      */
     @Throws(Exception::class)
-    private inline fun <reified T> parseResponse(response: Response<ApiResponse<T>>): T {
+    private inline fun <reified T> parseResponse(
+        response: Response<ApiResponse<T>>,
+        updateDeviceHash: Boolean = false,
+    ): T {
         app.config.update = response.body()?.update?.let { update ->
             if (update.versionCode > BuildConfig.VERSION_CODE) {
                 if (update.updateMandatory
@@ -144,6 +148,14 @@ class SzkolnyApi(val app: App) : CoroutineScope {
         }
 
         if (response.isSuccessful && response.body()?.success == true) {
+            // update the device's hash on success
+            if (updateDeviceHash) {
+                val hash = getDevice()?.toString()?.md5()
+                if (hash != null) {
+                    app.config.hash = hash
+                }
+            }
+
             if (Unit is T) {
                 return Unit
             }
@@ -168,7 +180,6 @@ class SzkolnyApi(val app: App) : CoroutineScope {
         throw SzkolnyApiException(body?.errors?.firstOrNull())
     }
 
-    @Throws(Exception::class)
     private fun getDevice() = run {
         val config = app.config
         val device = Device(
@@ -181,51 +192,50 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 appVersionCode = BuildConfig.VERSION_CODE,
                 syncInterval = app.config.sync.interval
         )
-        device.toString().md5().let {
-            if (it == config.hash)
-                null
-            else {
-                config.hash = it
-                device
-            }
-        }
+        val hash = device.toString().md5()
+        if (hash == config.hash)
+            return@run null
+        return@run device
     }
 
     @Throws(Exception::class)
     fun getEvents(profiles: List<Profile>, notifications: List<Notification>, blacklistedIds: List<Long>, lastSyncTime: Long): List<EventFull> {
         val teams = app.db.teamDao().allNow
 
+        val users = profiles.mapNotNull { profile ->
+            val config = app.config.getFor(profile.id)
+            val user = ServerSyncRequest.User(
+                profile.userCode,
+                profile.studentNameLong,
+                profile.studentNameShort,
+                profile.loginStoreType,
+                teams.filter { it.profileId == profile.id }.map { it.code }
+            )
+            val hash = user.toString().md5()
+            if (hash == config.hash)
+                return@mapNotNull null
+            return@mapNotNull user to config
+        }
+
         val response = api.serverSync(ServerSyncRequest(
                 deviceId = app.deviceId,
                 device = getDevice(),
                 userCodes = profiles.map { it.userCode },
-                users = profiles.mapNotNull { profile ->
-                    val config = app.config.getFor(profile.id)
-                    val user = ServerSyncRequest.User(
-                            profile.userCode,
-                            profile.studentNameLong,
-                            profile.studentNameShort,
-                            profile.loginStoreType,
-                            teams.filter { it.profileId == profile.id }.map { it.code }
-                    )
-                    user.toString().md5().let {
-                        if (it == config.hash)
-                            null
-                        else {
-                            config.hash = it
-                            user
-                        }
-                    }
-                },
+                users = users.keys(),
                 lastSync = lastSyncTime,
                 notifications = notifications.map { ServerSyncRequest.Notification(it.profileName ?: "", it.type, it.text) }
         )).execute()
-        val (events, hasBrowsers) = parseResponse(response)
+        val (events, hasBrowsers) = parseResponse(response, updateDeviceHash = true)
 
         hasBrowsers?.let {
             app.config.sync.webPushEnabled = it
         }
 
+        // update users' hashes on success
+        users.forEach { (user, config) ->
+            config.hash = user.toString().md5()
+        }
+
         val eventList = mutableListOf<EventFull>()
 
         events.forEach { event ->
@@ -270,7 +280,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 shareTeamCode = team.code,
                 event = event
         )).execute()
-        parseResponse(response)
+        parseResponse(response, updateDeviceHash = true)
     }
 
     @Throws(Exception::class)
@@ -284,7 +294,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 unshareTeamCode = team.code,
                 eventId = event.id
         )).execute()
-        parseResponse(response)
+        parseResponse(response, updateDeviceHash = true)
     }
 
     /*fun eventEditRequest(requesterName: String, event: Event): ApiResponse<Nothing>? {
@@ -301,7 +311,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 pairToken = pairToken
         )).execute()
 
-        return parseResponse(response).browsers
+        return parseResponse(response, updateDeviceHash = true).browsers
     }
 
     @Throws(Exception::class)
@@ -312,7 +322,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 action = "listBrowsers"
         )).execute()
 
-        return parseResponse(response).browsers
+        return parseResponse(response, updateDeviceHash = true).browsers
     }
 
     @Throws(Exception::class)
@@ -324,7 +334,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 browserId = browserId
         )).execute()
 
-        return parseResponse(response).browsers
+        return parseResponse(response, updateDeviceHash = true).browsers
     }
 
     @Throws(Exception::class)
@@ -335,7 +345,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 appVersion = BuildConfig.VERSION_NAME,
                 errors = errors
         )).execute()
-        parseResponse(response)
+        parseResponse(response, updateDeviceHash = true)
     }
 
     @Throws(Exception::class)
@@ -345,7 +355,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 device = getDevice(),
                 userCode = userCode
         )).execute()
-        parseResponse(response)
+        parseResponse(response, updateDeviceHash = true)
     }
 
     @Throws(Exception::class)
@@ -364,7 +374,7 @@ class SzkolnyApi(val app: App) : CoroutineScope {
                 text = text
         )).execute()
 
-        return parseResponse(response).message
+        return parseResponse(response, updateDeviceHash = true).message
     }
 
     @Throws(Exception::class)
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ext/ArrayExtensions.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ext/ArrayExtensions.kt
index 34da3ec0..e263627c 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ext/ArrayExtensions.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ext/ArrayExtensions.kt
@@ -59,20 +59,8 @@ fun SparseIntArray.values(): List<Int> {
     return result
 }
 
-fun <K, V> List<Pair<K, V>>.keys(): List<K> {
-    val result = mutableListOf<K>()
-    forEach { pair ->
-        result += pair.first
-    }
-    return result
-}
-fun <K, V> List<Pair<K, V>>.values(): List<V> {
-    val result = mutableListOf<V>()
-    forEach { pair ->
-        result += pair.second
-    }
-    return result
-}
+fun <K, V> List<Pair<K, V>>.keys() = map { it.first }
+fun <K, V> List<Pair<K, V>>.values() = map { it.second }
 
 fun <T> List<T>.toSparseArray(destination: SparseArray<T>, key: (T) -> Int) {
     forEach {