diff --git a/block/iscsi.c b/block/iscsi.c
index a015a52..9ce38b5 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1032,6 +1032,15 @@ static int iscsi_open(BlockDriverState *bs, const char *filename, int flags)
     if (iscsi_url != NULL) {
         iscsi_destroy_url(iscsi_url);
     }
+
+    /* Medium changer. We dont have any emulation for this so this must
+       be sg ioctl compatible. We force it to be sg, otherwise qemu will try
+       to read from the device to guess the image format.
+     */
+    if (iscsilun->type == TYPE_MEDIUM_CHANGER) {
+            bs->sg = 1;
+    }
+
     return 0;
 
 failed: