diff --git a/code/components/jomjol_flowcontroll/ClassFlowPostProcessing.cpp b/code/components/jomjol_flowcontroll/ClassFlowPostProcessing.cpp
index 351bcc0e9..360147ae6 100644
--- a/code/components/jomjol_flowcontroll/ClassFlowPostProcessing.cpp
+++ b/code/components/jomjol_flowcontroll/ClassFlowPostProcessing.cpp
@@ -757,13 +757,6 @@ bool ClassFlowPostProcessing::doFlow(string zwtime)
         NUMBERS[j]->ErrorMessageText = "";
         NUMBERS[j]->Value = -1;
 
-        /* calculate time difference BEFORE we overwrite the 'lastvalue' */
-        double difference = difftime(imagetime, NUMBERS[j]->lastvalue);      // in seconds
-
-        /* TODO:
-         * We could call `NUMBERS[j]->lastvalue = imagetime;` here and remove all other such calls further down.
-         * But we should check nothing breaks! */
-
         UpdateNachkommaDecimalShift();
 
         int previous_value = -1;
@@ -819,8 +812,6 @@ bool ClassFlowPostProcessing::doFlow(string zwtime)
             {
                 string _zw = NUMBERS[j]->name + ": Raw: " + NUMBERS[j]->ReturnRawValue + ", Value: " + NUMBERS[j]->ReturnValue + ", Status: " + NUMBERS[j]->ErrorMessageText;
                 LogFile.WriteToFile(ESP_LOG_INFO, TAG, _zw);
-               /* TODO to be discussed, see https://github.com/jomjol/AI-on-the-edge-device/issues/1617 */
-                NUMBERS[j]->lastvalue = imagetime;
 
                 WriteDataLog(j);
                 continue; // there is no number because there is still an N.
@@ -880,7 +871,6 @@ bool ClassFlowPostProcessing::doFlow(string zwtime)
                     NUMBERS[j]->ErrorMessageText = NUMBERS[j]->ErrorMessageText + "Neg. Rate - Read: " + zwvalue + " - Raw: " + NUMBERS[j]->ReturnRawValue + " - Pre: " + RundeOutput(NUMBERS[j]->PreValue, NUMBERS[j]->Nachkomma) + " "; 
                     NUMBERS[j]->Value = NUMBERS[j]->PreValue;
                     NUMBERS[j]->ReturnValue = "";
-                    NUMBERS[j]->lastvalue = imagetime;
 
                     string _zw = NUMBERS[j]->name + ": Raw: " + NUMBERS[j]->ReturnRawValue + ", Value: " + NUMBERS[j]->ReturnValue + ", Status: " + NUMBERS[j]->ErrorMessageText;
                     LogFile.WriteToFile(ESP_LOG_ERROR, TAG, _zw);
@@ -894,7 +884,7 @@ bool ClassFlowPostProcessing::doFlow(string zwtime)
         #ifdef SERIAL_DEBUG
             ESP_LOGD(TAG, "After AllowNegativeRates: Value %f", NUMBERS[j]->Value);
         #endif
-
+        double difference = difftime(imagetime, NUMBERS[j]->lastvalue);      // in seconds
         difference /= 60;  
         NUMBERS[j]->FlowRateAct = (NUMBERS[j]->Value - NUMBERS[j]->PreValue) / difference;
         NUMBERS[j]->ReturnRateValue =  to_string(NUMBERS[j]->FlowRateAct);
@@ -913,7 +903,6 @@ bool ClassFlowPostProcessing::doFlow(string zwtime)
                 NUMBERS[j]->Value = NUMBERS[j]->PreValue;
                 NUMBERS[j]->ReturnValue = "";
                 NUMBERS[j]->ReturnRateValue = "";
-                NUMBERS[j]->lastvalue = imagetime;
 
                 string _zw = NUMBERS[j]->name + ": Raw: " + NUMBERS[j]->ReturnRawValue + ", Value: " + NUMBERS[j]->ReturnValue + ", Status: " + NUMBERS[j]->ErrorMessageText;
                 LogFile.WriteToFile(ESP_LOG_ERROR, TAG, _zw);
@@ -929,7 +918,7 @@ bool ClassFlowPostProcessing::doFlow(string zwtime)
         NUMBERS[j]->ReturnChangeAbsolute = RundeOutput(NUMBERS[j]->Value - NUMBERS[j]->PreValue, NUMBERS[j]->Nachkomma);
         NUMBERS[j]->PreValue = NUMBERS[j]->Value;
         NUMBERS[j]->PreValueOkay = true;
-        NUMBERS[j]->lastvalue = imagetime;
+        NUMBERS[j]->lastvalue = imagetime; // must only be set in case of good value !!!
 
         NUMBERS[j]->ReturnValue = RundeOutput(NUMBERS[j]->Value, NUMBERS[j]->Nachkomma);
         NUMBERS[j]->ReturnPreValue = RundeOutput(NUMBERS[j]->PreValue, NUMBERS[j]->Nachkomma);