diff --git a/usr.bin/mkimg/bsd.c b/usr.bin/mkimg/bsd.c
index a93ed0dc5461..03af5cd2e863 100644
--- a/usr.bin/mkimg/bsd.c
+++ b/usr.bin/mkimg/bsd.c
@@ -80,7 +80,7 @@ bsd_write(lba_t imgsz, void *bootcode)
 	} else
 		memset(buf, 0, BBSIZE);
 
-	imgsz = ncyls * nheads * nsecs;
+	imgsz = (lba_t)ncyls * nheads * nsecs;
 	error = image_set_size(imgsz);
 	if (error) {
 		free(buf);
diff --git a/usr.bin/mkimg/vtoc8.c b/usr.bin/mkimg/vtoc8.c
index 05a3ce8ac2bc..8eb7d24080bd 100644
--- a/usr.bin/mkimg/vtoc8.c
+++ b/usr.bin/mkimg/vtoc8.c
@@ -71,7 +71,7 @@ vtoc8_write(lba_t imgsz, void *bootcode __unused)
 	int error, n;
 	uint16_t ofs, sum;
 
-	imgsz = ncyls * nheads * nsecs;
+	imgsz = (lba_t)ncyls * nheads * nsecs;
 
 	memset(&vtoc8, 0, sizeof(vtoc8));
 	sprintf(vtoc8.ascii, "FreeBSD%lldM",