Java logging dependency for a low-level library

I inherited a lower-level open source Java network library. The library is intended to be used by higher-level application protocol libraries which are in turn used by application code. My library, as left by the previous maintainer, has no dependencies and is built via Ant. The build artifact is a simple jar that others can drop into their projects.

I am in the process of converting the library to be built with Maven. As I'm doing this, I'm considering possibly adding slf4j as a dependency. Currently, when something goes wrong, stack traces or other information is spit out to System.out or System.err. I know that that's not always very helpful, but these outputs only happen at 10 to 15 places in the code and are rarely executed.

So what do you think? Keep the library simple with zero dependencies or introduce slf4j?