diff --git a/include/dbus_utility.hpp b/include/dbus_utility.hpp
index 2dd3d97..ac5970d 100644
--- a/include/dbus_utility.hpp
+++ b/include/dbus_utility.hpp
@@ -53,9 +53,9 @@
                                  std::string& result)
 {
     int count = 0;
-    auto first = path.begin();
-    auto last = path.end();
-    for (auto it = path.begin(); it < path.end(); it++)
+    std::string::const_iterator first = path.begin();
+    std::string::const_iterator last = path.end();
+    for (std::string::const_iterator it = path.begin(); it < path.end(); it++)
     {
         // skip first character as it's either a leading slash or the first
         // character in the word
@@ -85,7 +85,8 @@
     {
         first++;
     }
-    result = path.substr(first - path.begin(), last - first);
+    result = path.substr(static_cast<size_t>(first - path.begin()),
+                         static_cast<size_t>(last - first));
     return true;
 }