diff --git a/libisofs/fs_image.c b/libisofs/fs_image.c
index ccb7935..817668d 100644
--- a/libisofs/fs_image.c
+++ b/libisofs/fs_image.c
@@ -2344,6 +2344,12 @@ int iso_image_import(IsoImage *image, IsoDataSource *src,
                 goto import_revert;
             }
             image->bootcat->image->image = (IsoFile*)node;
+            
+            /* warn about hidden images */
+            iso_msg_submit(image->id, ISO_EL_TORITO_HIDDEN, 0, 
+                           "Found hidden El-Torito image. Its size could not "
+                           "be figure out, so image modify or boot image "
+                           "patching may lead to bad results.");
         }
         if (image->bootcat->node == NULL) {
             IsoNode *node = calloc(1, sizeof(IsoBoot));
diff --git a/libisofs/libiso_msgs.h b/libisofs/libiso_msgs.h
index b9c61bd..36bd2c4 100644
--- a/libisofs/libiso_msgs.h
+++ b/libisofs/libiso_msgs.h
@@ -550,6 +550,7 @@ Range "vreixo"              :  0x00030000 to 0x0003ffff
  0x0003feb4 (HINT,MEDIUM)  = Unsupported volume descriptor found
  0x0003feb3 (WARNING,HIGH) = El-Torito related warning
  0x0003feb2 (SORRY,HIGH)   = Image write cancelled
+ 0x0003feb1 (WARNING,HIGH) = El-Torito image is hidden
 
 
 ------------------------------------------------------------------------------
diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index a871d26..d39e7ce 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -3113,4 +3113,7 @@ const char *iso_image_fs_get_biblio_file_id(IsoImageFilesystem *fs);
 /** Image write cancelled (SORRY,HIGH, -334) */
 #define ISO_IMAGE_WRITE_CANCELED        0xE030FEB2
 
+/** El-Torito image is hidden (WARNING,HIGH, -335) */
+#define ISO_EL_TORITO_HIDDEN            0xD030FEB1
+
 #endif /*LIBISO_LIBISOFS_H_*/
diff --git a/libisofs/messages.c b/libisofs/messages.c
index 087c166..b5d6d20 100644
--- a/libisofs/messages.c
+++ b/libisofs/messages.c
@@ -201,6 +201,8 @@ const char *iso_error_to_msg(int errcode)
         return "El-Torito related warning";
     case ISO_IMAGE_WRITE_CANCELED: 
         return "Image write cancelled";
+    case ISO_EL_TORITO_HIDDEN: 
+        return "El-Torito image is hidden";
     default:
         return "Unknown error";
     }