diff --git a/ext/tpx/RedlichKwong.cpp b/ext/tpx/RedlichKwong.cpp
index 17121f60b..6128d70aa 100644
--- a/ext/tpx/RedlichKwong.cpp
+++ b/ext/tpx/RedlichKwong.cpp
@@ -17,7 +17,7 @@ namespace tpx {
     double RedlichKwong::hresid(){
         double hh = m_b * (Rho/m_mw);
 	double hresid_mol_RT =  z() - 1.0 
-                             - (1.5*m_a/(m_b*8314.3*pow(T,1.5)))*log(1.0 + hh);
+                                - (1.5*m_a/(m_b*8314.3*T*sqrt(T)))*log(1.0 + hh);
         return 8314.3*T*hresid_mol_RT/m_mw;
     }
 
@@ -25,7 +25,7 @@ namespace tpx {
         double hh = m_b * (Rho/m_mw);
         //cout << "hh = " << hh << endl;
 	double sresid_mol_R =  log(z()*(1.0 - hh)) 
-                             - (0.5*m_a/(m_b*8314.3*pow(T,1.5)))*log(1.0 + hh);
+                               - (0.5*m_a/(m_b*8314.3*T*sqrt(T)))*log(1.0 + hh);
         double sp = 8314.3*sresid_mol_R/m_mw;
         //cout << "sresid = " << sp << endl;
         return sp;