lib::with::preamble places a code hook at the beginning of @inc, and then relies upon that hook remaining at $INC[0]. In a suitably complicated codebase, there is likely to be one module which modifies the head of @inc, and some subsequent module which violates the constraints that lib::with::preamble is intended to enforce. Included in the patc…

sticky-inc.patch

diff --git a/Makefile.PL b/Makefile.PL
index cfc4d6d..8e90634 100644
--- Makefile.PL
+++ Makefile.PL
@@ -8,5 +8,8 @@ WriteMakefile(
   NAME => 'lib-with-preamble',
   VERSION_FROM => 'lib/lib/with/preamble.pm',
   PM_FILTER => 'perl my/filter',
-  PREREQ_PM => { 'PerlIO::via::dynamic' => 0.02 },
+  PREREQ_PM => {
+    'PerlIO::via::dynamic' => 0.02,
+    'Array::Sticky'        => 0.01,
+  },
 );
diff --git a/lib/lib/with/preamble.pm b/lib/lib/with/preamble.pm
index a6ad586..744c540 100644
--- lib/lib/with/preamble.pm
+++ lib/lib/with/preamble.pm
@@ -4,6 +4,7 @@ use strict;
 use warnings FATAL => 'all';
 use File::Spec;
 use PerlIO::via::dynamic;
+use Array::Sticky::INC;
 
 our $VERSION = '0.001000'; # 0.1.0
 
@@ -31,6 +32,7 @@ sub import {
   my ($class, $preamble, @libs) = @_;
   return unless defined($preamble) and @libs;
   unshift @INC, [ \&require_with_preamble, $preamble, @libs ];
+  Array::Sticky::INC->make_sticky;
 }
 
 1;
diff --git a/t/lib/has_strict_violation.pm b/t/lib/has_strict_violation.pm
new file mode 100644
index 0000000..68547d4
--- /dev/null
+++ t/lib/has_strict_violation.pm
@@ -0,0 +1,5 @@
+package has_strict_violation;
+
+$y = 10;
+
+1;
diff --git a/t/lib/is_okay.pm b/t/lib/is_okay.pm
new file mode 100644
index 0000000..e272ccf
--- /dev/null
+++ t/lib/is_okay.pm
@@ -0,0 +1,6 @@
+package is_okay;
+
+use screws_up_INC;
+use has_strict_violation;
+
+1;
diff --git a/t/lib/screws_up_INC.pm b/t/lib/screws_up_INC.pm
new file mode 100644
index 0000000..26b34eb
--- /dev/null
+++ t/lib/screws_up_INC.pm
@@ -0,0 +1,5 @@
+package screws_up_INC;
+
+sub import { shift @INC }
+
+1;
diff --git a/t/sticky-inc-hooks.t b/t/sticky-inc-hooks.t
new file mode 100644
index 0000000..ab57186
--- /dev/null
+++ t/sticky-inc-hooks.t
@@ -0,0 +1,10 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use Test::More tests => 1;
+
+use lib::with::preamble 'use strict;', 't/lib', './lib';
+
+eval { require is_okay };
+like( $@, qr/Global symbol "\$y" requires explicit package name.*has_strict_violation\.pm line 3/, 'our @INC hook stays in place' );