diff --git a/src/OpenFOAM/meshes/boundBox/boundBoxI.H b/src/OpenFOAM/meshes/boundBox/boundBoxI.H
index aa95e05411783622bf5534eaa11adc064f42edab..0379a93ee8a446ec12f9901680715cafed0a821e 100644
--- a/src/OpenFOAM/meshes/boundBox/boundBoxI.H
+++ b/src/OpenFOAM/meshes/boundBox/boundBoxI.H
@@ -143,7 +143,7 @@ inline Foam::scalar Foam::boundBox::avgDim() const
 }
 
 
-Foam::label Foam::boundBox::nDim() const
+inline Foam::label Foam::boundBox::nDim() const
 {
     label ngood = 0;