diff --git a/src/lagrangian/intermediate/submodels/CloudFunctionObjects/CloudFunctionObject/CloudFunctionObject.H b/src/lagrangian/intermediate/submodels/CloudFunctionObjects/CloudFunctionObject/CloudFunctionObject.H
index 5baf0f7ae95fd82cfcc635db6c84e47633c162b1..51306608859b8ba443250a37e4adfe3fd42e4875 100644
--- a/src/lagrangian/intermediate/submodels/CloudFunctionObjects/CloudFunctionObject/CloudFunctionObject.H
+++ b/src/lagrangian/intermediate/submodels/CloudFunctionObjects/CloudFunctionObject/CloudFunctionObject.H
@@ -46,6 +46,9 @@ SourceFiles
 namespace Foam
 {
 
+class polyPatch;
+class tetIndices;
+
 /*---------------------------------------------------------------------------*\
                     Class CloudFunctionObject Declaration
 \*---------------------------------------------------------------------------*/