diff --git a/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.C b/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.C
index 81897565c..915c5efa0 100644
--- a/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.C
+++ b/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.C
@@ -58,8 +58,8 @@ Foam::waveAlphaFvPatchScalarField::waveAlphaFvPatchScalarField
 :
     mixedFvPatchScalarField(p, iF),
     UName_(dict.lookupOrDefault<word>("U", "U")),
-    liquid_(dict.lookupOrDefault<bool>("liquid", true)),
-    inletOutlet_(dict.lookupOrDefault<bool>("inletOutlet", true))
+    liquid_(dict.lookupOrDefault<Switch>("liquid", true)),
+    inletOutlet_(dict.lookupOrDefault<Switch>("inletOutlet", true))
 {
     if (dict.found("value"))
     {
@@ -171,7 +171,8 @@ void Foam::waveAlphaFvPatchScalarField::write
 {
     mixedFvPatchScalarField::write(os);
     writeEntryIfDifferent<word>(os, "U", "U", UName_);
-    writeEntryIfDifferent<bool>(os, "inletOutlet", true, inletOutlet_);
+    writeEntryIfDifferent<Switch>(os, "inletOutlet", true, inletOutlet_);
+    writeEntryIfDifferent<Switch>(os, "liquid", true, inletOutlet_);
 }
 
 
diff --git a/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.H b/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.H
index c97b49547..049804d64 100644
--- a/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.H
+++ b/src/waves/derivedFvPatchFields/waveAlpha/waveAlphaFvPatchScalarField.H
@@ -79,14 +79,14 @@ class waveAlphaFvPatchScalarField
         word UName_;
 
         //- Is this alpha field that of the liquid under the wave?
-        const bool liquid_;
+        const Switch liquid_;
 
         //- Act as an inlet/outlet patch? If false, the alpha field will be set
         //  by the wave model even during outflow. This may apply the wave model
         //  more accurately, but it might also be unstable. If true, the alpha
         //  boundary condition will be zero gradient when the flow reverses, as
         //  is usual.
-        const bool inletOutlet_;
+        const Switch inletOutlet_;
 
 
 public: