diff --git a/diffusivityModel/GasState/GasState.C b/diffusivityModel/GasState/GasState.C
index 9a0b86e..e5fa34f 100644
--- a/diffusivityModel/GasState/GasState.C
+++ b/diffusivityModel/GasState/GasState.C
@@ -25,8 +25,6 @@ License
 
 #include "GasState.H"
 
-#include "diffusivityModel.H"
-
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
 // const dataType Foam::GasState::staticData();
@@ -37,17 +35,6 @@ License
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-inline const Foam::PtrList<Foam::GasState::thermoType> &Foam::GasState::thermos() const
-{
-    return diffusivityModel::thermoData();
-}
-
-
-inline const Foam::GasState::thermoType &Foam::GasState::thermos(label i) const
-{
-    return thermos()[i];
-}
-
 
 // * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
diff --git a/diffusivityModel/GasState/GasState.H b/diffusivityModel/GasState/GasState.H
index 85ac785..3e7af3d 100644
--- a/diffusivityModel/GasState/GasState.H
+++ b/diffusivityModel/GasState/GasState.H
@@ -40,6 +40,8 @@ SourceFiles
 #include "constants.H"
 #include "scalarField.H"
 
+#include "diffusivityModel.H"
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
diff --git a/diffusivityModel/GasState/GasStateI.H b/diffusivityModel/GasState/GasStateI.H
index 154d9a7..3d52658 100644
--- a/diffusivityModel/GasState/GasStateI.H
+++ b/diffusivityModel/GasState/GasStateI.H
@@ -36,6 +36,18 @@ License
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+inline const Foam::PtrList<Foam::GasState::thermoType> &Foam::GasState::thermos() const
+{
+    return diffusivityModel::thermoData();
+}
+
+
+inline const Foam::GasState::thermoType &Foam::GasState::thermos(label i) const
+{
+    return thermos()[i];
+}
+
+
 inline Foam::scalar Foam::GasState::T() const
 {
     return T_;