Mixing Exception/Non-Exception Code

I am working in C++ (under Linux) with a set of code that I did not write and does not use exceptions. In fact, in the Makefile, the compiler flag -fno-exceptions is defined. Also, I need to compile directly with this code (for contractual and other reasons). I''ve contacted the authors of the code and their opinion is: "Try it, let us know how it works." What are the ramifications of mixing code that uses exceptions with code that does not? Are there extra steps that I need to make sure that the underlying code does not break? Am I headed towards destabilization?