diff --git a/src/easylogging++.cc b/src/easylogging++.cc
index 0d7dea0c9..c61e64363 100644
--- a/src/easylogging++.cc
+++ b/src/easylogging++.cc
@@ -1900,7 +1900,7 @@ Logger* RegisteredLoggers::get(const std::string& id, bool forceCreation) {
     logger_->m_logBuilder = m_defaultLogBuilder;
     registerNew(id, logger_);
     LoggerRegistrationCallback* callback = nullptr;
-    for (const std::pair<std::string, base::type::LoggerRegistrationCallbackPtr>& h
+    for (const std::pair<const std::string, base::type::LoggerRegistrationCallbackPtr>& h
          : m_loggerRegistrationCallbacks) {
       callback = h.second.get();
       if (callback != nullptr && callback->enabled()) {
@@ -2490,7 +2490,7 @@ void LogDispatcher::dispatch(void) {
   }
   LogDispatchCallback* callback = nullptr;
   LogDispatchData data;
-  for (const std::pair<std::string, base::type::LogDispatchCallbackPtr>& h
+  for (const std::pair<const std::string, base::type::LogDispatchCallbackPtr>& h
        : ELPP->m_logDispatchCallbacks) {
     callback = h.second.get();
     if (callback != nullptr && callback->enabled()) {
@@ -2697,7 +2697,7 @@ PerformanceTracker::~PerformanceTracker(void) {
       data.init(this);
       data.m_formattedTimeTaken = formattedTime;
       PerformanceTrackingCallback* callback = nullptr;
-      for (const std::pair<std::string, base::type::PerformanceTrackingCallbackPtr>& h
+      for (const std::pair<const std::string, base::type::PerformanceTrackingCallbackPtr>& h
            : ELPP->m_performanceTrackingCallbacks) {
         callback = h.second.get();
         if (callback != nullptr && callback->enabled()) {
@@ -2724,7 +2724,7 @@ void PerformanceTracker::checkpoint(const std::string& id, const char* file, bas
     data.m_func = func;
     data.m_formattedTimeTaken = formattedTime;
     PerformanceTrackingCallback* callback = nullptr;
-    for (const std::pair<std::string, base::type::PerformanceTrackingCallbackPtr>& h
+    for (const std::pair<const std::string, base::type::PerformanceTrackingCallbackPtr>& h
          : ELPP->m_performanceTrackingCallbacks) {
       callback = h.second.get();
       if (callback != nullptr && callback->enabled()) {