diff --git a/src/utils/packet_counter.cpp b/src/utils/packet_counter.cpp
index 13d415738..e47e83e7c 100644
--- a/src/utils/packet_counter.cpp
+++ b/src/utils/packet_counter.cpp
@@ -3,7 +3,7 @@
  * @author Martin Pulec     <pulec@cesnet.cz>
  */
 /*
- * Copyright (c) 2012 CESNET, z. s. p. o.
+ * Copyright (c) 2012-2023 CESNET, z. s. p. o.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -42,7 +42,6 @@
 #endif // defined HAVE_CONFIG_H
 
 #include "utils/packet_counter.h"
-#include <cassert>
 #include <map>
 #include <vector>
 
@@ -50,35 +49,19 @@ using std::map;
 using std::vector;
 
 struct packet_counter {
-        packet_counter(int num_substreams) {
-                this->num_substreams = num_substreams;
-
-                substream_data.reserve(num_substreams);
-                for(int i = 0; i < num_substreams; ++i) {
-                        substream_data.push_back(map<int, map<int, int> > ());
-                }
-        }
-
-        ~packet_counter() {
-        }
+        explicit packet_counter(int ns) : substream_data(ns) {}
 
         void register_packet(int substream_id, int bufnum, int offset, int len) {
-                assert(substream_id < num_substreams); 
-
-                substream_data[substream_id][bufnum][offset] = len;
+                substream_data.at(substream_id)[bufnum][offset] = len;
         }
 
         int get_total_bytes() {
                 int ret = 0;
 
-                for(int i = 0; i < num_substreams; ++i) {
-                        for(map<int, map<int, int> >::const_iterator it = substream_data[i].begin();
-                                       it != substream_data[i].end();
-                                       ++it) {
-                                for(map<int, int>::const_iterator it2 = it->second.begin();
-                                               it2 != it->second.end();
-                                               ++it2) {
-                                        ret += it2->second;
+                for (auto &&chan : substream_data) {
+                        for (auto &&buffer : chan) {
+                                for (auto &&packet : buffer.second) {
+                                        ret += packet.second;
                                 }
                         }
                 }
@@ -89,12 +72,11 @@ struct packet_counter {
         int get_all_bytes() {
                 int ret = 0;
 
-                for(int i = 0; i < num_substreams; ++i) {
-                        for(map<int, map<int, int> >::const_iterator it = substream_data[i].begin();
-                                       it != substream_data[i].end();
-                                       ++it) {
-                                if(!it->second.empty()) {
-                                        ret += (--it->second.end())->first + (--it->second.end())->second;
+                for (auto &&chan : substream_data) {
+                        for (auto &buf : chan) {
+                                if (!buf.second.empty()) {
+                                        ret += (--buf.second.end())->first +
+                                               (--buf.second.end())->second;
                                 }
                         }
                 }
@@ -103,27 +85,20 @@ struct packet_counter {
         }
 
         void clear() {
-                for(int i = 0; i < num_substreams; ++i) {
-                        substream_data[i].clear();
+                for (auto &&chan : substream_data) {
+                        chan.clear();
                 }
         }
 
         vector<map<int, map<int, int> > > substream_data;
-        int num_substreams;
 };
 
 struct packet_counter *packet_counter_init(int num_substreams) {
-        struct packet_counter *state;
-        
-        state = new packet_counter(num_substreams);
-
-        return state;
+        return new packet_counter(num_substreams);
 }
 
 void packet_counter_destroy(struct packet_counter *state) {
-        if(state) {
-                delete state;
-        }
+        delete state;
 }
 
 void packet_counter_register_packet(struct packet_counter *state, unsigned int substream_id, unsigned int bufnum,
@@ -144,7 +119,7 @@ int packet_counter_get_all_bytes(struct packet_counter *state)
 
 int packet_counter_get_channels(struct packet_counter *state)
 {
-        return state->num_substreams;
+        return (int) state->substream_data.size();
 }
 
 void packet_counter_clear(struct packet_counter *state)