diff --git a/src/thermophysicalModels/thermophysicalProperties/liquidProperties/NH3/NH3.C b/src/thermophysicalModels/thermophysicalProperties/liquidProperties/NH3/NH3.C
index daf69bf..5c1ebf0 100644
--- a/src/thermophysicalModels/thermophysicalProperties/liquidProperties/NH3/NH3.C
+++ b/src/thermophysicalModels/thermophysicalProperties/liquidProperties/NH3/NH3.C
@@ -77,7 +77,7 @@ Foam::NH3::NH3()
     mug_("mug", 4.1855e-08, 9.8060e-01, 3.0800e+01, 0),
     kappa_("kappa", 1.1606e+00, -2.2840e-03, 0, 0, 0, 0),
     kappag_("kappag", -4.5900e-02, 1.6520e-01, -1.7078e+03, 0),
-    sigma_("sigma", 9.1200e-02, 1.1028e+00, 0, 0, 0, 0),
+    sigma_("sigma", Tc(), 9.1200e-02, 1.1028e+00, 0, 0, 0),
     D_("D", 14.9, 20.1, W(), 28),
     hf_(h_.value(Tstd))
 {}