http://sourceforge.net/p/gphoto/bugs/945/

diff -up libgphoto2-2.5.1.1/camlibs/ptp2/ptp.c~ libgphoto2-2.5.1.1/camlibs/ptp2/ptp.c
--- libgphoto2-2.5.1.1/camlibs/ptp2/ptp.c~	2013-01-27 19:17:03.000000000 +0100
+++ libgphoto2-2.5.1.1/camlibs/ptp2/ptp.c	2013-05-04 11:21:32.558255859 +0200
@@ -1877,6 +1877,11 @@ ptp_canon_eos_getobjectinfoex (
 	if (ret != PTP_RC_OK)
 		return ret;
 
+	if (!data) {
+		*nrofentries = 0;
+		return PTP_RC_OK;
+	}
+
 	*nrofentries = dtoh32a(data);
 	*entries = malloc(*nrofentries * sizeof(PTPCANONFolderEntry));
 	if (!*entries)