diff --git a/src/cosim/timer.cpp b/src/cosim/timer.cpp
index 99026229..101407aa 100644
--- a/src/cosim/timer.cpp
+++ b/src/cosim/timer.cpp
@@ -104,8 +104,7 @@ class real_time_timer::impl
         metrics_->total_average_real_time_factor = relativeSimTime.count() / (1.0 * relativeRealTime.count());
 
         if (sampling_period_to_monitor_.has_value()) {
-            const auto elapsedRealTime =
-                tick_period_match_ ? currentTime - rtStartTime_ : std::chrono::duration_cast<cosim::duration>(currentTime - rtStartTime_);
+            const auto elapsedRealTime = currentTime - rtStartTime_;
 
             if (elapsedRealTime > sampling_period_to_monitor_.value()) {
                 update_rolling_average_real_time_factor(currentTime, currentSimulationTime, elapsedRealTime);
@@ -113,7 +112,7 @@ class real_time_timer::impl
         } else if (rtCounter_ >= config_->steps_to_monitor.load()) {
             const auto elapsedRealTime = currentTime - rtStartTime_;
 
-            update_rolling_average_real_time_factor(currentTime, currentSimulationTime, elapsedRealTime);
+            update_rolling_average_real_time_factor(currentTime, currentSimulationTime, std::chrono::duration_cast<cosim::duration>(elapsedRealTime));
         }
         rtCounter_++;
     }