diff --git a/src/OpenFOAM/db/functionObjects/functionObjectFile/functionObjectFile.H b/src/OpenFOAM/db/functionObjects/functionObjectFile/functionObjectFile.H
index 8710b92b7a..f4c0ab1178 100644
--- a/src/OpenFOAM/db/functionObjects/functionObjectFile/functionObjectFile.H
+++ b/src/OpenFOAM/db/functionObjects/functionObjectFile/functionObjectFile.H
@@ -64,7 +64,7 @@ private:
         const objectRegistry& obr_;
 
         //- Prefix
-        const word& prefix_;
+        const word prefix_;
 
         //- File names
         wordHashSet names_;