I tried to import a Gtk enumeration constant: ;; Local Variables: ;; compile-command: "gsc -cc-options \"`pkg-config --cflags gtk+-2.0`\" -ld-options \"`pkg-config --libs gtk+-2.0`\" -exe enum.scm" ;; End: (c-declare "#include <gtk/gtk.h>") (c-define-type GtkWindowType "GtkWindowType") (define gtk-window-toplevel ((c-lambda () GtkWindowType "___result = GTK_WINDOW_TOPLEVEL;"))) (write gtk-window-toplevel) But I get a segmentation fault when I run the program. When I use int instead of the enum type the code does not segfault: (define gtk-window-toplevel ((c-lambda () int "___result = GTK_WINDOW_TOPLEVEL;"))) Does this mean, that I have to ignore all C enum types and treat them as ints? The documentation for c-define-type does not say much about enumerations: http://www.iro.umontreal.ca/~gambit/doc/gambit-c.html#c_002ddefine_002dtype