diff --git a/src/OpenFOAM/meshes/primitiveShapes/plane/plane.H b/src/OpenFOAM/meshes/primitiveShapes/plane/plane.H
index d6ed5f6962..6769a17082 100644
--- a/src/OpenFOAM/meshes/primitiveShapes/plane/plane.H
+++ b/src/OpenFOAM/meshes/primitiveShapes/plane/plane.H
@@ -126,23 +126,28 @@ public:
     // Constructors
 
         //- Construct from normal vector through the origin
-        plane(const vector& normalVector);
+        explicit plane(const vector& normalVector);
 
         //- Construct from normal vector and point in plane
-        plane(const point& basePoint, const vector& normalVector);
+        explicit plane(const point& basePoint, const vector& normalVector);
 
         //- Construct from three points in plane
-        plane(const point& point1, const point& point2, const point& point3);
+        explicit plane
+        (
+            const point& point1,
+            const point& point2,
+            const point& point3
+        );
 
         //- Construct from coefficients for the
         //  plane equation: ax + by + cz + d = 0
-        plane(const scalarList& C);
+        explicit plane(const scalarList& C);
 
         //- Construct from dictionary
-        plane(const dictionary& planeDict);
+        explicit plane(const dictionary& planeDict);
 
         //- Construct from Istream. Assumes the base + normal notation.
-        plane(Istream& is);
+        explicit plane(Istream& is);
 
 
     // Member Functions