diff --git a/extras/volume_id/vol_id.c b/extras/volume_id/vol_id.c
index 3c75bdaa2f5..2b53085c72a 100644
--- a/extras/volume_id/vol_id.c
+++ b/extras/volume_id/vol_id.c
@@ -145,6 +145,7 @@ int main(int argc, char *argv[])
 
 	if (ioctl(vid->fd, BLKGETSIZE64, &size) != 0)
 		size = 0;
+	dbg("BLKGETSIZE64=%llu", size);
 
 	if (volume_id_probe_all(vid, 0, size) == 0)
 		goto print;
diff --git a/extras/volume_id/volume_id/util.c b/extras/volume_id/volume_id/util.c
index 62b96a36570..d1271a86be6 100644
--- a/extras/volume_id/volume_id/util.c
+++ b/extras/volume_id/volume_id/util.c
@@ -197,7 +197,7 @@ set:
 
 uint8_t *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
 {
-	size_t buf_len;
+	ssize_t buf_len;
 
 	dbg("get buffer off 0x%llx(%llu), len 0x%zx", (unsigned long long) off, (unsigned long long) off, len);
 	/* check if requested area fits in superblock buffer */
@@ -224,7 +224,7 @@ uint8_t *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
 			}
 			dbg("got 0x%zx (%zi) bytes", buf_len, buf_len);
 			id->sbbuf_len = buf_len;
-			if (buf_len < off + len) {
+			if ((size_t)buf_len < off + len) {
 				dbg("requested 0x%zx bytes, got only 0x%zx bytes", len, buf_len);
 				return NULL;
 			}
@@ -261,7 +261,7 @@ uint8_t *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
 			dbg("got 0x%zx (%zi) bytes", buf_len, buf_len);
 			id->seekbuf_off = off;
 			id->seekbuf_len = buf_len;
-			if (buf_len < len) {
+			if ((size_t)buf_len < len) {
 				dbg("requested 0x%zx bytes, got only 0x%zx bytes", len, buf_len);
 				return NULL;
 			}