diff --git a/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C b/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C
index 3dc2e5c42e..403ec924b5 100644
--- a/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C
+++ b/src/OpenFOAM/primitives/functions/Function1/Function1/Function1.C
@@ -67,7 +67,9 @@ void Foam::Function1<Type>::convertTimeBase(const Time&)
 template<class Type>
 Type Foam::Function1<Type>::value(const scalar x) const
 {
-    NotImplemented;
+    FatalErrorInFunction
+        << "Evaluation is not defined for " << type() << " functions"
+        << exit(FatalError);
 
     return Zero;
 }
@@ -76,7 +78,9 @@ Type Foam::Function1<Type>::value(const scalar x) const
 template<class Type>
 Type Foam::Function1<Type>::integrate(const scalar x1, const scalar x2) const
 {
-    NotImplemented;
+    FatalErrorInFunction
+        << "Integration is not defined for " << type() << " functions"
+        << exit(FatalError);
 
     return Zero;
 }
diff --git a/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C b/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C
index 46ad1b2c3e..433a34dc49 100644
--- a/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C
+++ b/src/OpenFOAM/primitives/functions/Function1/makeFunction1s.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -74,7 +74,10 @@ Foam::Function1Types::Constant<Foam::label>::integrate
     const scalarField& x2
 ) const
 {
-    NotImplemented;
+    FatalErrorInFunction
+        << "Evaluation is not defined for " << type() << " functions"
+        << exit(FatalError);
+
     return tmp<Field<label>>(new Field<label>(x1.size()));
 }