diff --git a/library/src/utilities.cpp b/library/src/utilities.cpp
index d44278c..09906f1 100644
--- a/library/src/utilities.cpp
+++ b/library/src/utilities.cpp
@@ -408,7 +408,10 @@ uint32_t Utilities::getMaximalParkingPrice(Configuration const *cfg, PaymentMeth
 
 uint32_t Utilities::getTimeRangeStep(Configuration const *cfg, int step, PaymentMethod methodId) {
     if (methodId == PaymentMethod::Progressive) {
-        return std::max((int)cfg->TimeRange.find(step)->second.time_range_to_in_minutes_from_start, 0);
+        Configuration::TimeRangeType::const_iterator it = cfg->TimeRange.find(step);
+        if (it != cfg->TimeRange.cend()) {
+            return std::max((int)(it->second.time_range_to_in_minutes_from_start), 0);
+        }
     }
 
     return 0;