[SBCL][FFI][CL-GTK2][Мэджик] непредсказуемое поведение FFI

(in-package :gtk)
(load-foreign-library "libgtksourceview-2.0.so")

(define-g-object-class "GtkSourceLanguageManager" source-language-manager
                       (:export t :interfaces
                        ())
			())

(defcfun gtk-source-language-manager-get-language-ids
	:pointer
	(language-manager (g-object source-language-manager)))

(defun get-language-list (language-manager)
	(let ((pointer (gtk-source-language-manager-get-language-ids language-manager)))
	(loop with i = 0
	      until (null-pointer-p (mem-aref pointer :pointer i))
	      collect (mem-aref pointer :string i)
	      do (incf i))))

(setq *lm* (make-instance 'source-language-manager))
(get-language-list *lm*)

(make-instance 'source-language-manager)
(get-language-list *)

* (make-instance 'source-language-manager)

(<unknown>:4278): GLib-GObject-CRITICAL **: g_object_newv: assertion `G_TYPE_IS_OBJECT (object_type)' failed

(<unknown>:4278): GLib-GObject-CRITICAL **: g_object_add_toggle_ref: assertion `G_IS_OBJECT (object)' failed

(<unknown>:4278): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed

#<SOURCE-LANGUAGE-MANAGER {C587AB9}>
* (get-language-list *)

(<unknown>:4278): GtkSourceView-CRITICAL **: gtk_source_language_manager_get_language_ids: assertion `GTK_IS_SOURCE_LANGUAGE_MANAGER (lm)' failed
CORRUPTION WARNING in SBCL pid 4278(tid 3085097760):
Memory fault at 0 (pc=0xc52a6f5, sp=0xb7985ba8)
The integrity of this image is possibly compromised.
Continuing with fingers crossed.

debugger invoked on a SB-SYS:MEMORY-FAULT-ERROR in thread #<THREAD "initial thread" RUNNING {BECF659}>:
  Unhandled memory fault at #x0.

Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [ABORT] Exit debugger, returning to top level.

(SB-SYS:MEMORY-FAULT-ERROR)
0]