diff --git a/minix/commands/repartition/repartition.c b/minix/commands/repartition/repartition.c
index ace391b60..bd7e82af4 100644
--- a/minix/commands/repartition/repartition.c
+++ b/minix/commands/repartition/repartition.c
@@ -262,8 +262,8 @@ int main(int argc, char **argv)
 			pe->size= part_limit - pe->lowsec;
 		}
 
-		entry.base= pe->lowsec * SECTOR_SIZE;
-		entry.size= pe->size * SECTOR_SIZE;
+		entry.base= (off_t)pe->lowsec * SECTOR_SIZE;
+		entry.size= (off_t)pe->size * SECTOR_SIZE;
 		if (diocntl(makedev(hd_major, device), DSETP, &entry) < 0)
 			fatal(dev_file);