pkg-config ne trouve pas gtk+-3.0

Indique ici que le paquet gtk+-3.0 n'a pas été trouvé :

karl@karl-ux303ln:~$ pkg-config --cflags gtk+-3.0
Package gtk+-3.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `gtk+-3.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'gtk+-3.0' found

Cependant, j'ai apparemment installé gtk3 :

karl@karl-ux303ln:~$ dpkg -l libgtk* | grep -e '^i' | grep -e 'libgtk-*[0-9]'
ii  libgtk-3-0:amd64                            3.14.15-0ubuntu1~14.04~ricotz1                              amd64        GTK+ graphical user interface library
ii  libgtk-3-bin                                3.14.15-0ubuntu1~14.04~ricotz1                              amd64        programs for the GTK+ graphical user interface library
ii  libgtk-3-common                             3.14.15-0ubuntu1~14.04~ricotz1                              all          common files for the GTK+ graphical user interface library
ii  libgtk2.0-0:amd64                           2.24.23-0ubuntu1.3                                          amd64        GTK+ graphical user interface library
ii  libgtk2.0-bin                               2.24.23-0ubuntu1.3                                          amd64        programs for the GTK+ graphical user interface library
ii  libgtk2.0-common                            2.24.23-0ubuntu1.3                                          all          common files for the GTK+ graphical user interface library

Cependant je n'arrive pas à trouver le fichier gtk+-3.0.pc :

karl@karl-ux303ln:~$ sudo find / -name "gtk+-3.0.pc"
karl@karl-ux303ln:~$ 

Des idées ? J'essaie d'utiliser cmake mais il ne trouve pas gtk3.