diff --git a/check_size_consistency.pl b/check_size_consistency.pl
index b7abee0..dad865c 100644
--- a/check_size_consistency.pl
+++ b/check_size_consistency.pl
@@ -2,6 +2,7 @@
 use lib "/usr/share/BackupPC/lib";
 use BackupPC::Lib;
 use BackupPC::CGI::Lib;
+use POSIX;
 use JSON;
 
 # We need to switch to backuppc UID/GID