--- a/src/OpenFOAM/db/IOobject/IOobject.C
+++ b/src/OpenFOAM/db/IOobject/IOobject.C
@@ -94,9 +94,9 @@ bool Foam::IOobject::IOobject::fileNameComponents
         // check afterwards
         name.string::operator=(path);
     }
-    else if (first == 0)
+    else if (path.isAbsolute())
     {
-        // Leading '/'. Absolute fileName
+        // called with absolute path
         string::size_type last = path.rfind('/');
         instance = path.substr(0, last);