diff --git a/routermon/routermon.py b/routermon/routermon.py
index ae18ac9..55e8ba2 100644
--- a/routermon/routermon.py
+++ b/routermon/routermon.py
@@ -51,8 +51,8 @@ def main() -> int:
             # Calcolo della velocita' interfaccia a ogni ciclo
             for n, _ in enumerate(if_stats):
                 if_name = if_stats[n].pop('name')
-                if_stats[n]['rx-rate'] = int((if_stats[n]['rx-bytes']-if_stats_old[n]['rx-bytes'])/(now-last))
-                if_stats[n]['tx-rate'] = int((if_stats[n]['tx-bytes']-if_stats_old[n]['tx-bytes'])/(now-last))
+                if_stats[n]['rx-rate'] = int((if_stats[n]['rx-bytes']-if_stats_old[n]['rx-bytes'])/(INTERVAL))
+                if_stats[n]['tx-rate'] = int((if_stats[n]['tx-bytes']-if_stats_old[n]['tx-bytes'])/(INTERVAL))
                 if_points.append(
                     dict2Point('interfaces', if_stats[n], {'interface': if_name})
                 )
@@ -63,10 +63,9 @@ def main() -> int:
 
             # Salvo ultimo punto per il giro successivo
             if_stats_old = if_stats
-            last = time.time()
             LOGGER.debug(f"\nInterfaces: {json.dumps(if_stats, indent = 2)}")
             LOGGER.debug(f"\nResources: {json.dumps(hw_stats, indent = 2)}")
-            time.sleep(INTERVAL)
+            time.sleep(INTERVAL-(last-now))
         except Exception as e:
             print(f"Unexpected exception: [{e}]")
             return 1