diff --git a/app/src/main/java/it/reyboz/bustorino/backend/mato/MQTTMatoClient.kt b/app/src/main/java/it/reyboz/bustorino/backend/mato/MQTTMatoClient.kt
--- a/app/src/main/java/it/reyboz/bustorino/backend/mato/MQTTMatoClient.kt
+++ b/app/src/main/java/it/reyboz/bustorino/backend/mato/MQTTMatoClient.kt
@@ -375,13 +375,20 @@
         val currentTimeStamp = makeUnixTimestamp()
         var c = 0
         positionsLock.withLock{
-            for ((k, manyp) in currentPositions.entries) {
-                for ((t, p) in manyp.entries) {
+            for ((k, posByVeh) in currentPositions) {
+                /*for (t in posByVeh.keys.toList()) {      // iterate over snapshot to avoid modification error
+                    val p = posByVeh[t] ?: continue
                     if (currentTimeStamp - p.timestamp > timeMins * 60) {
-                        manyp.remove(t)
+                        posByVeh.remove(t)
                         c += 1
                     }
                 }
+                 */
+                c+=posByVeh.entries.removeIf{ el ->
+                    currentTimeStamp - el.value.timestamp > timeMins * 60
+                }.let {
+                    if(it) 1 else 0
+                }
             }
         }
         Log.d(DEBUG_TAG, "Removed $c positions older than $timeMins minutes")