[Lazarus] Fatal: Can't open include file "lcl_defines.inc"

[Giuliano Colla]

As of Lazarus 1.3 r45254M FPC 2.6.2 i386-linux-gtk 2
I'm unable to compile a package which used to compile without troubles.

The error shown is:
/home/colla/Applicazioni/lazarus/lcl/lclproc.pas(22,2) Fatal: Can't open 
include file "lcl_defines.inc"

Adding

$(LazarusDir)/lcl/include

to the paths in the package compiler options doesn't help.
I also tried adding the lcl/include path to the open project compiler 
options (just in case) but no change.

Editing the lclproc file to
{$I include/lcl_defines.inc}
only takes one step forward: lclproc.pas compiles, but next file which 
includes from lcl/include doesn't.

The full IDE compilation, if I don't include my custom package, is 
carried on without troubles.

Any hint?

Giuliano