diff --git a/IBPSA/Fluid/BaseClasses/FlowModels/Validation/BasicFlowFunction_dp_DerivativeCheck.mo b/IBPSA/Fluid/BaseClasses/FlowModels/Validation/BasicFlowFunction_dp_DerivativeCheck.mo
index e3f1c0903c..fdcc56b385 100644
--- a/IBPSA/Fluid/BaseClasses/FlowModels/Validation/BasicFlowFunction_dp_DerivativeCheck.mo
+++ b/IBPSA/Fluid/BaseClasses/FlowModels/Validation/BasicFlowFunction_dp_DerivativeCheck.mo
@@ -21,7 +21,6 @@ equation
     k = k,
     m_flow_turbulent=m_flow_turbulent);
   der(m_flow) = der(m_flow_comp);
-  der_m_flow_dp = IBPSA.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp_der(dp);
   err = m_flow-m_flow_comp;
   assert(abs(err) < 1E-3, "Error in implementation.");
 annotation (