gcc 2.6.0 is known to have such bugs, especially when compiling C++ programs, but it can also happen for later versions. (This is usually a genuine gcc bug, not something special to djgpp.) Using #if 0 ... #endif paradigm, narrow the offending code fragment. If this fragment is syntactically and semantically correct, then rewrite it as equivalent, but syntactically different one. As an extreme measure, don't optimize.