HI i get this error

Error 33 The call is ambiguous between the following methods or properties: 'System.Math.Ceiling(decimal)' and 'System.Math.Ceiling(double)' C:\Documents and Settings\B\Desktop\Lewies_Min177620812004\MiniHexEdit\Form1.cs 491 22 MiniHexEdit
On this line:

Code:
int items = (int)System.Math.Ceiling((listView1.Height - headerFooter) / itemHeight);
Any ideas?