diff --git a/services/backup/src/Tools.cpp b/services/backup/src/Tools.cpp
--- a/services/backup/src/Tools.cpp
+++ b/services/backup/src/Tools.cpp
@@ -3,6 +3,7 @@
 #include "GlobalConstants.h"
 #include "GlobalTools.h"
 
+#include <algorithm>
 #include <chrono>
 #include <cstdlib>
 #include <random>
@@ -53,19 +54,19 @@
 }
 
 std::size_t getUtf8Length(std::string &str) {
-  std::size_t result = 0;
-  const char *ptr = str.data();
-  const char *end = ptr + str.size();
 
-  while (ptr < end) {
-    int next = std::mblen(ptr, end - ptr);
-    if (next == -1) {
-      throw std::runtime_error("strlen_mb(): conversionn error");
-    }
-    ptr += next;
-    ++result;
-  }
-  return result;
+  // How it works?
+  // Every byte of multibyte utf8 character starts with information about its
+  // own type. Additional bytes always start with a 2bit sequence "10xx xxxx"
+  // (which is equal to hex 0x80). To count the length of utf8 string we need
+  // to skip these bytes, so we use a bitmask.
+  //
+  // We need to compare first 2 bits of a byte, so we use bitwise operator
+  // & with mask 0xC0. If returned value is equal to 0x80, we skip it.
+
+  return std::count_if(str.begin(), str.end(), [](char c) {
+    return (static_cast<unsigned char>(c) & 0xC0) != 0x80;
+  });
 }
 
 } // namespace tools