If you use Qmake from the command line, I would assume that it would take the header files from the directory QMake itself is in. For example you call:

Qt Code: 
  1. C:\QT\4.6\bin\make.exe
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That qt automaticly uses the header files from: C:\QT\4.6\include...

But I don't know how those files are stored in a linux system which you seem to be using (I only program using Windows).

So maybe you can try this, and maybe someone else around here knows more about that.

Good luck!