diff --git a/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.C b/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.C
index 36c85f7f71..41ead49a94 100644
--- a/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.C
+++ b/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2015-2020 OpenCFD Ltd.
+    Copyright (C) 2015-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -90,16 +90,6 @@ Foam::tmp<Foam::Field<Type>> Foam::Function1Types::Constant<Type>::value
 }
 
 
-template<class Type>
-Foam::tmp<Foam::Field<Type>> Foam::Function1Types::Constant<Type>::integrate
-(
-    const scalarField& x1,
-    const scalarField& x2
-) const
-{
-    return (x2 - x1)*value_;
-}
-
 template<class Type>
 void Foam::Function1Types::Constant<Type>::writeData(Ostream& os) const
 {
diff --git a/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.H b/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.H
index 978c39db31..03ad51f379 100644
--- a/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.H
+++ b/src/OpenFOAM/primitives/functions/Function1/Constant/Constant.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2015-2020 OpenCFD Ltd.
+    Copyright (C) 2015-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -73,7 +73,6 @@ public:
     TypeName("constant");
 
 
-
     // Generated Methods
 
         //- No copy assignment
@@ -118,26 +117,11 @@ public:
         //- Return value as a function of (scalar) independent variable
         virtual tmp<Field<Type>> value(const scalarField& x) const;
 
-        //- Integrate between two (scalar) values
-        virtual tmp<Field<Type>> integrate
-        (
-            const scalarField& x1,
-            const scalarField& x2
-        ) const;
-
         //- Write in dictionary format
         virtual void writeData(Ostream& os) const;
 };
 
 
-template<>
-tmp<Field<label>> Function1Types::Constant<label>::integrate
-(
-    const scalarField& x1,
-    const scalarField& x2
-) const;
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Function1Types
diff --git a/src/OpenFOAM/primitives/functions/Function1/Constant/ConstantI.H b/src/OpenFOAM/primitives/functions/Function1/Constant/ConstantI.H
index cae94af7bd..5e05dd30f8 100644
--- a/src/OpenFOAM/primitives/functions/Function1/Constant/ConstantI.H
+++ b/src/OpenFOAM/primitives/functions/Function1/Constant/ConstantI.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2017 OpenFOAM Foundation
+    Copyright (C) 2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -43,7 +44,7 @@ inline Type Foam::Function1Types::Constant<Type>::integrate
     const scalar x2
 ) const
 {
-    return (x2 - x1)*value_;
+    return Type((x2 - x1)*value_);
 }
 
 
diff --git a/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C b/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C
index f635078a46..84900b63f7 100644
--- a/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C
+++ b/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -60,7 +60,7 @@ template<class Type>
 Type Foam::Function1<Type>::value(const scalar x) const
 {
     NotImplemented;
-    return Zero;
+    return Type();
 }
 
 
@@ -80,7 +80,7 @@ template<class Type>
 Type Foam::Function1<Type>::integrate(const scalar x1, const scalar x2) const
 {
     NotImplemented;
-    return Zero;
+    return Type();
 }
 
 
diff --git a/src/OpenFOAM/primitives/functions/Function1/Table/TableBase.C b/src/OpenFOAM/primitives/functions/Function1/Table/TableBase.C
index 8c1fdb2595..3b12a3d4c2 100644
--- a/src/OpenFOAM/primitives/functions/Function1/Table/TableBase.C
+++ b/src/OpenFOAM/primitives/functions/Function1/Table/TableBase.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -285,7 +285,7 @@ Type Foam::Function1Types::TableBase<Type>::value(const scalar x) const
     // Use interpolator
     interpolator().valueWeights(xDash, currentIndices_, currentWeights_);
 
-    Type t = currentWeights_[0]*table_[currentIndices_[0]].second();
+    Type t(currentWeights_[0]*table_[currentIndices_[0]].second());
     for (label i = 1; i < currentIndices_.size(); i++)
     {
         t += currentWeights_[i]*table_[currentIndices_[i]].second();
@@ -305,7 +305,7 @@ Type Foam::Function1Types::TableBase<Type>::integrate
     // Use interpolator
     interpolator().integrationWeights(x1, x2, currentIndices_, currentWeights_);
 
-    Type sum = currentWeights_[0]*table_[currentIndices_[0]].second();
+    Type sum(currentWeights_[0]*table_[currentIndices_[0]].second());
     for (label i = 1; i < currentIndices_.size(); i++)
     {
        sum += currentWeights_[i]*table_[currentIndices_[i]].second();
diff --git a/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C b/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C
index 3ecf9c0e12..680c49149c 100644
--- a/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C
+++ b/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -59,6 +59,13 @@ License
     makeFunction1Type(Scale, Type);                                            \
     makeFunction1Type(LimitRange, Type);
 
+#define makeFieldFunction1s(Type)                                              \
+    makeFunction1(Type);                                                       \
+    makeFunction1Type(Constant, Type);                                         \
+    makeFunction1Type(Uniform, Type);                                          \
+    makeFunction1Type(Table, Type);                                            \
+    makeFunction1Type(TableFile, Type);                                        \
+
 namespace Foam
 {
     makeFunction1(label);
@@ -69,19 +76,8 @@ namespace Foam
     makeFunction1s(sphericalTensor);
     makeFunction1s(symmTensor);
     makeFunction1s(tensor);
-}
 
-
-template<>
-Foam::tmp<Foam::Field<Foam::label>>
-Foam::Function1Types::Constant<Foam::label>::integrate
-(
-    const scalarField& x1,
-    const scalarField& x2
-) const
-{
-    NotImplemented;
-    return tmp<Field<label>>::New(x1.size());
+    makeFieldFunction1s(scalarField);
 }