diff --git a/scripts/nix-copy-closure.in b/scripts/nix-copy-closure.in
index f4d186256..875ca9817 100755
--- a/scripts/nix-copy-closure.in
+++ b/scripts/nix-copy-closure.in
@@ -1,5 +1,6 @@
 #! @perl@ -w @perlFlags@
 
+use strict;
 use Nix::SSH;
 use Nix::Config;
 use Nix::Store;