BOOST_ASSERT( ( 0 <= PingsFailedCount ) && ( PingsFailedCount <= PingsPerformedCount ) );
 }
 
-bool PingAnalyzer::exceeded_ping_failed_count_limit()
+bool PingAnalyzer::exceeded_ping_failed_count_limit() const
 {
     BOOST_ASSERT( ( 0 <= LimitPingFailPercentage ) && ( LimitPingFailPercentage <= 100 ) );
     BOOST_ASSERT( ( 0 <= PingsFailedCount ) && ( PingsFailedCount <= PingsPerformedCount ) );
 
     void reset_ping_counters();
     void increase_ping_performed_count();
     void increase_ping_failed_count();
-    bool exceeded_ping_failed_count_limit();
+    bool exceeded_ping_failed_count_limit() const;
     bool tried_all_resolved_ip() const;
 
 private: