diff --git a/sys/boot/common/bcache.c b/sys/boot/common/bcache.c
index 4bb9082bea2..c935c90f938 100644
--- a/sys/boot/common/bcache.c
+++ b/sys/boot/common/bcache.c
@@ -303,7 +303,9 @@ read_strategy(void *devdata, int rw, daddr_t blk, size_t offset,
 	    break;
     }
 
-    size = i * bcache_blksize;
+    if (size > i * bcache_blksize)
+	size = i * bcache_blksize;
+
     if (size != 0) {
 	bcopy(bc->bcache_data + (bcache_blksize * BHASH(bc, blk)) + offset,
 	    buf, size);