diff --git a/.perlcriticrc b/.perlcriticrc
index ea6efc689a..5f6aee8e45 100644
--- a/.perlcriticrc
+++ b/.perlcriticrc
@@ -44,3 +44,12 @@ severity = 5
 
 [Variables::ProhibitUnusedVariables]
 severity = 5
+
+[Modules::ProhibitMultiplePackages]
+severity = 5
+
+[Modules::RequireEndWithOne]
+severity = 5
+
+[ValuesAndExpressions::ProhibitConstantPragma]
+severity = 5
diff --git a/lib/Munin/Master/Node.pm b/lib/Munin/Master/Node.pm
index c0256273b1..bf3074fe41 100644
--- a/lib/Munin/Master/Node.pm
+++ b/lib/Munin/Master/Node.pm
@@ -793,6 +793,7 @@ sub _merge_into_str_no_dup
 }
 
 # Defines the URL::scheme for munin
+## no critic qw(Modules::ProhibitMultiplePackages)
 package URI::munin;
 
 # We are like a generic server
diff --git a/lib/Munin/Node/SpoolWriter.pm b/lib/Munin/Node/SpoolWriter.pm
index dfecf0eb15..674841a600 100644
--- a/lib/Munin/Node/SpoolWriter.pm
+++ b/lib/Munin/Node/SpoolWriter.pm
@@ -16,10 +16,11 @@ use Munin::Common::Utils qw( is_valid_hostname );
 
 use Params::Validate qw( :all );
 use List::Util qw( first );
+use Readonly;
 
-use constant DEFAULT_TIME => 86_400;      # put 1 day of results into a spool file
-use constant MAXIMUM_AGE  => 7;           # remove spool files more than a week old
-use constant DEFAULT_HOSTNAME => 'munin.example.com';
+Readonly my $DEFAULT_TIME => 86_400;      # put 1 day of results into a spool file
+Readonly my $MAXIMUM_AGE  => 7;           # remove spool files more than a week old
+Readonly my $DEFAULT_HOSTNAME => 'munin.example.com';
 
 sub _snap_to_epoch_boundary { my $self = shift; return $_[0] - ($_[0] % $self->{interval_size}) }
 
@@ -50,19 +51,19 @@ sub new {
     $self->{interval_size} = first { defined($_) and $_ > 0 } (
         $validated->{interval_size},
         $self->{metadata}->{interval_size},
-        DEFAULT_TIME
+        $DEFAULT_TIME
     );
 
     $self->{interval_keep} = first { defined($_) and $_ > 0 } (
         $validated->{interval_keep},
         $self->{metadata}->{interval_keep},
-        MAXIMUM_AGE,
+        $MAXIMUM_AGE,
     );
 
     $self->{hostname} = first { defined($_) and is_valid_hostname($_) } (
         $validated->{hostname},
         $self->{metadata}->{hostname},
-        DEFAULT_HOSTNAME,
+        $DEFAULT_HOSTNAME,
     );
 
     return $self;
diff --git a/lib/Munin/Plugin/Framework.pm b/lib/Munin/Plugin/Framework.pm
index c9ccf37d62..756181923b 100644
--- a/lib/Munin/Plugin/Framework.pm
+++ b/lib/Munin/Plugin/Framework.pm
@@ -177,3 +177,5 @@ sub run {
     }
   }
 }
+
+1;
diff --git a/lib/Munin/Plugin/HTTP.pm b/lib/Munin/Plugin/HTTP.pm
index 90d7f52d9e..6b4a36a3da 100644
--- a/lib/Munin/Plugin/HTTP.pm
+++ b/lib/Munin/Plugin/HTTP.pm
@@ -111,3 +111,5 @@ sub get_basic_credentials {
 
   return $isproxy ? () : ($ENV{'http_username'}, $ENV{'http_password'});
 }
+
+1;
diff --git a/script/munin-httpd b/script/munin-httpd
index 401d6b1588..67a0dd3c83 100755
--- a/script/munin-httpd
+++ b/script/munin-httpd
@@ -30,8 +30,6 @@ use warnings;
 # Trust PERL5LIB from environment
 use lib map { /(.*)/ } split(/:/, ($ENV{PERL5LIB} || ''));
 
-package Munin::Master::Http;
-
 use HTTP::Server::Simple::CGI::PreFork;
 use base qw(HTTP::Server::Simple::CGI::PreFork);
 
@@ -59,8 +57,6 @@ sub handle_request
 	}
 }
 
-package main;
-
 $ENV{PATH} = '/usr/bin:/bin';
 
 # start the server on port 4948