diff --git a/src/OpenFOAM/primitives/bools/Switch/Switch.H b/src/OpenFOAM/primitives/bools/Switch/Switch.H
index b37e2bbb403d5e50d381c4a13926fef0e02b8c44..4eaa2dd12b532e9618e6489ff29d2b23d01d92f3 100644
--- a/src/OpenFOAM/primitives/bools/Switch/Switch.H
+++ b/src/OpenFOAM/primitives/bools/Switch/Switch.H
@@ -176,9 +176,10 @@ public:
         }
 
         //- Assignment from bool
-        void operator=(const bool b)
+        const Switch& operator=(const bool b)
         {
             switch_ = (b ? Switch::TRUE : Switch::FALSE);
+            return *this;
         }