Library being included when it shouldn't be

I made a library called 'qdebug' a few weeks ago and tested it with a few sketches.

Today I've created a new sketch. This is derived from the 'qdebug' files, so some of the files and functions have the same name (but different return types in functions).

When I try to compile it I get:

In file included from C:\Users\chris\Documents\Arduino\libraries\qdebug/commonc.h:11:0,

                 from sketch\common.c:12:

C:\Users\chris\Documents\Arduino\libraries\qdebug/mySerial.h:18:7: error: conflicting types for 'printc'

  void printc(char c);


In file included from sketch\common.c:11:0:

sketch\serial.h:28:7: note: previous declaration of 'printc' was here

   int printc(char c);


but I do not have any call to #include "qdebug.h" in my sketch. So why is it picking up these defintions? Why is it even looking in "libraries\qdebug/mySerial.h"?