diff --git a/residue.cpp b/residue.cpp
index 57e20cd..6e205b2 100644
--- a/residue.cpp
+++ b/residue.cpp
@@ -872,8 +872,7 @@ int residue(double t,
 		sum1=ZERO;
 		for (k = 1; k <=nsp; k++) {
 			sum=sum+wdot(k)*enthalpy(k);
-			sum1=sum1+(Cp(k)/data->gas->molecularWeight(k-1))*rho
-			     *HALF*(YVmhalf(k)+YVphalf(k));
+			sum1=sum1+(Cp(k)/data->gas->molecularWeight(k-1))*HALF*(YVmhalf(k)+YVphalf(k));
 		}
 		sum=sum*Cantera::GasConstant*T(j);
 		sum1=sum1*Cantera::GasConstant;