It has been tested with SBCL on Debian unstable.
With SBCL, this package uses sbcl-specific way to access errno variable (sb-alien:get-errno). With other CL compilers, errno variable accessed via uffi:def-foreign-var, but unfortunately, errno is no more a simple variable in today's C libraries, and this approach is unlikely to work with them. This means what you may need to edit source code to add appropriate compiler-specific code to get-errno function. (If someone knows a portable way to access errno with modern C libraries besides using conditional compilation, drop a note here. Also maybe a list of errno-getting functions for various compilers would help)
A version 0.4 use errno again, if SBCL then sb-alien:get-errno, if CMUCL then unix:unix-errno, else __errno_location.