> gcc -c -g -gnatec=/gps/gps-3.0.0/gps/gnat.adc -O2 -gnatn -gnatws -I- I'd suggest building GPS 3.1.3, available from libre.adacore.com, which comes with the proper gtkada sources (gps-3.1.3-gpl-src.tgz and gtkada-gps-3.1.3-src.tgz). Here you clearly have a version mismatch between the GPS sources and the GtkAda sources. Arno