The line shown appears to be correct - I tried it with values for the variables. So, I hate to ask the basic questions but it has got to come down to one of these:
1. Are you using warnings and strict? If you are not using strict then you might wish to consider setting it on as a test using -Mstrict on the command-line.
2. Are you certain that the line you show is really the line it is reporting the error on? Could it be using a different version of the module?

By the way, 5.12 reports the variable name that is uninitialized.