diff --git a/libisofs/fs_image.c b/libisofs/fs_image.c
index ec8184d..4b3f4e2 100644
--- a/libisofs/fs_image.c
+++ b/libisofs/fs_image.c
@@ -3229,8 +3229,19 @@ int iso_file_get_old_image_sections(IsoFile *file, int *section_count,
          * to get the sections. This break encapsultation, but safes memory as
          * we don't need to store the sections in the IsoFile node.
          */
-        FSrcStreamData *data = file->stream->data;
-        ImageFileSourceData *ifsdata = data->src->data;
+        IsoStream *stream = file->stream;
+        FSrcStreamData *data;
+        ImageFileSourceData *ifsdata;
+
+        /* <<< ts A90327 : provisory patch on SIGSEGV */
+        if (stream->class->type[0] != 'f' || stream->class->type[1] != 's' ||
+            stream->class->type[2] != 'r' || stream->class->type[3] != 'c')
+            return 0;
+
+        /* >>> need a method to get the most original stream */
+
+        data = file->stream->data;
+        ifsdata = data->src->data;
 
         *section_count = ifsdata->nsections;
         *sections = malloc(ifsdata->nsections *