diff --git a/dlls/gphoto2.ds/gphoto2_i.h b/dlls/gphoto2.ds/gphoto2_i.h
index e92a5e83ae5..89c4bc08a33 100644
--- a/dlls/gphoto2.ds/gphoto2_i.h
+++ b/dlls/gphoto2.ds/gphoto2_i.h
@@ -244,7 +244,7 @@ TW_UINT16 GPHOTO2_RGBResponseSet
 
 /* UI function */
 BOOL DoCameraUI(void);
-HWND TransferringDialogBox(HWND dialog, DWORD progress);
+HWND TransferringDialogBox(HWND dialog, LONG progress);
 
 #ifdef HAVE_GPHOTO2
 /* Helper function for GUI */
diff --git a/dlls/gphoto2.ds/ui.c b/dlls/gphoto2.ds/ui.c
index d36d7dec01b..e9d2f874c0f 100644
--- a/dlls/gphoto2.ds/ui.c
+++ b/dlls/gphoto2.ds/ui.c
@@ -274,12 +274,12 @@ static INT_PTR CALLBACK ProgressProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM
 	    return FALSE;
 }   
 
-HWND TransferringDialogBox(HWND dialog, DWORD progress)
+HWND TransferringDialogBox(HWND dialog, LONG progress)
 {
 	if (!dialog)
 		dialog = CreateDialogW(GPHOTO2_instance,
 				(LPWSTR)MAKEINTRESOURCE(IDD_DIALOG1), NULL, ProgressProc);
-		                
+
 	if (progress == -1)
 	{
 		EndDialog(dialog,0);