wineps.drv: Avoid a potential NULL pointer dereference (coccicheck).

[Michael Stefaniuc]

---
 dlls/wineps.drv/init.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/dlls/wineps.drv/init.c b/dlls/wineps.drv/init.c
index 685a56a..935e686 100644
--- a/dlls/wineps.drv/init.c
+++ b/dlls/wineps.drv/init.c
@@ -271,7 +271,7 @@ static LPDEVMODEA DEVMODEdupWtoA(HANDLE heap, const DEVMODEW *dmW)
     LPDEVMODEA dmA;
     DWORD size;
     BOOL Formname;
-    ptrdiff_t off_formname = (const char *)dmW->dmFormName - (const char *)dmW;
+    ptrdiff_t off_formname = FIELD_OFFSET(DEVMODEW, dmFormName);
 
     if(!dmW) return NULL;
     Formname = (dmW->dmSize > off_formname);
-- 
1.7.1