Yet another leak in Xlib

[Po Lu]

Doesn't this leak found by Valgrind sound like a bug?
For reference, here's how I'm calling XRegisterIMInstantiateCallback:

  XSetLocaleModifiers ("");
  XRegisterIMInstantiateCallback (compositor.display,
				  XrmGetDatabase (compositor.display),
				  (char *) compositor.resource_name,
				  (char *) compositor.app_name,
				  IMInstantiateCallback, NULL);

and XMODIFIERS is:

  @im=ibus

and the leak is:

==67186== 408 bytes in 1 blocks are definitely lost in loss record 272 of 344
==67186==    at 0x484A464: calloc (vg_replace_malloc.c:1328)
==67186==    by 0x490935F: _XimOpenIM (in /usr/lib64/libX11.so.6.4.0)
==67186==    by 0x490F386: _XimRegisterIMInstantiateCallback (in /usr/lib64/libX11.so.6.4.0)
==67186==    by 0x48FBDBD: XRegisterIMInstantiateCallback (in /usr/lib64/libX11.so.6.4.0)
==67186==    by 0x4456B5: tiInitTextInput (text_input.c:837)
==67186==    by 0x4079C5: dlMain (loader.c:205)
==67186==    by 0x4079F2: main (loader.c:214)

Thanks.