Using the armV5 compiler in keil with c99 and cpp11

I have a mixed project in Keil IDE with c and cpp files. I want to compile the cpp files with the cpp11 standard, but when I set the --cpp11 in the misc controls it compiles the C files as cpp files (and obviously that causes a lot of compilation errors) the c files needs to be compiles in the c99 standard. I ended up setting the --cpp11 flag just on a specific group to work around the issue. But I'm wondering if there is a way to set both of the rules (--cpp11 and --c99) to the entire project?