diff --git a/block/blk-map.c b/block/blk-map.c
index 4849fa3..0f4b4b8 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -217,6 +217,12 @@
 		return PTR_ERR(bio);
 
 	if (bio->bi_size != len) {
+		/*
+		 * Grab an extra reference to this bio, as bio_unmap_user()
+		 * expects to be able to drop it twice as it happens on the
+		 * normal IO completion path
+		 */
+		bio_get(bio);
 		bio_endio(bio, 0);
 		bio_unmap_user(bio);
 		return -EINVAL;