diff --git a/bin/ngcp-api-ping b/bin/ngcp-api-ping
index 7bbed9c..0fb5d1a 100755
--- a/bin/ngcp-api-ping
+++ b/bin/ngcp-api-ping
@@ -14,8 +14,8 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "verbose",
+    'help|h' => sub { usage() },
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -42,7 +42,7 @@ sub main {
     my $client = NGCP::API::Client->new(verbose => $opts->{verbose});
 
     my $uri = '/api/domains/';
-    my $res = $client->request("GET", $uri);
+    my $res = $client->request('GET', $uri);
 
     if (defined $res->as_hash->{total_count}) {
         print "API is up\n";
diff --git a/bin/ngcp-create-customer b/bin/ngcp-create-customer
index 4d78883..d1f73c9 100755
--- a/bin/ngcp-create-customer
+++ b/bin/ngcp-create-customer
@@ -16,11 +16,11 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "billing_profile_id=i",
-    "contact_id=i",
-    "type=s",
-    "verbose",
+    'help|h' => sub { usage() },
+    'billing_profile_id=i',
+    'contact_id=i',
+    'type=s',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -50,7 +50,7 @@ sub main {
     my $uri = '/api/customers/';
     my %data = map { $_ => $opts->{$_} }
                     qw(billing_profile_id contact_id type status);
-    my $res = $client->request("POST", $uri, \%data);
+    my $res = $client->request('POST', $uri, \%data);
     print $res->result."\n";
 
     return !$res->is_success;
diff --git a/bin/ngcp-create-domain b/bin/ngcp-create-domain
index 61ffbf0..2bbf381 100755
--- a/bin/ngcp-create-domain
+++ b/bin/ngcp-create-domain
@@ -17,12 +17,12 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "domain=s",
-    "reseller_id=i",
-    "skip_xmpp",
-    "skip_sip",
-    "verbose",
+    'help|h' => sub { usage() },
+    'domain=s',
+    'reseller_id=i',
+    'skip_xmpp',
+    'skip_sip',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -58,9 +58,9 @@ sub main {
     my $uri = '/api/domains/';
     my %data = map { $_ => $opts->{$_} } qw(reseller_id domain);
     foreach my $elem (qw(skip_xmpp skip_sip)) {
-        $data{"_" . $elem . "_reload"} = $opts->{$elem};
+        $data{'_' . $elem . '_reload'} = $opts->{$elem};
     }
-    my $res = $client->request("POST", $uri, \%data);
+    my $res = $client->request('POST', $uri, \%data);
     print $res->result."\n";
 
     return !$res->is_success;
diff --git a/bin/ngcp-create-subscriber b/bin/ngcp-create-subscriber
index 051c99f..cc9a8c9 100755
--- a/bin/ngcp-create-subscriber
+++ b/bin/ngcp-create-subscriber
@@ -15,17 +15,17 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "customer_id=i",
-    "username|u=s",
-    "password|p=s",
-    "domain|d=s",
-    "admin|s=i",
-    "cc|c=i",
-    "ac|a=i",
-    "sn|n=i",
-    "webpassword|w=s",
-    "verbose",
+    'help|h' => sub { usage() },
+    'customer_id=i',
+    'username|u=s',
+    'password|p=s',
+    'domain|d=s',
+    'admin|s=i',
+    'cc|c=i',
+    'ac|a=i',
+    'sn|n=i',
+    'webpassword|w=s',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -69,7 +69,7 @@ sub main {
     } else {
         $data{domain_id} = $tmp->{id};
     }
-    my $res = $client->request("POST", $uri, \%data);
+    my $res = $client->request('POST', $uri, \%data);
     print $res->result."\n";
 
     return !$res->is_success;
diff --git a/bin/ngcp-credit-warning b/bin/ngcp-credit-warning
index 49093f1..d907071 100755
--- a/bin/ngcp-credit-warning
+++ b/bin/ngcp-credit-warning
@@ -25,8 +25,8 @@ my $opts = {
 my $config;
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "verbose",
+    'help|h' => sub { usage() },
+    'verbose',
 ) or usage();
 
 sub check_params {
diff --git a/bin/ngcp-delete-domain b/bin/ngcp-delete-domain
index 379d25f..5af67fc 100755
--- a/bin/ngcp-delete-domain
+++ b/bin/ngcp-delete-domain
@@ -17,11 +17,11 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "domain=s",
-    "skip_xmpp",
-    "skip_sip",
-    "verbose",
+    'help|h' => sub { usage() },
+    'domain=s',
+    'skip_xmpp',
+    'skip_sip',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -49,13 +49,13 @@ sub main {
     my $client = NGCP::API::Client->new(verbose => $opts->{verbose});
 
     # domain_id
-    my $dom = $client->request("GET", "/api/domains/?domain=".$opts->{domain});
+    my $dom = $client->request('GET', '/api/domains/?domain='.$opts->{domain});
     if ($dom->as_hash->{total_count} != 1) {
         die "Domain $opts->{domain} not found\n";
     }
 
     my $uri = '/api/domains/';
-    my %data = map { "_".$_."_reload" => $opts->{$_} } qw(skip_xmpp skip_sip);
+    my %data = map { '_'.$_.'_reload' => $opts->{$_} } qw(skip_xmpp skip_sip);
     my $dom_id;
     my $tmp = $dom->as_hash->{_embedded}->{'ngcp:domains'};
     if (ref $tmp eq 'ARRAY') {
@@ -65,7 +65,7 @@ sub main {
     }
     die "Domain $opts->{domain} not found\n" unless $dom_id;
     $uri .= $dom_id;
-    my $res = $client->request("DELETE", $uri, \%data);
+    my $res = $client->request('DELETE', $uri, \%data);
     print $res->result."\n";
 
     return !$res->is_success;
diff --git a/bin/ngcp-fraud-notifier b/bin/ngcp-fraud-notifier
index de33e7e..cdb2a9d 100755
--- a/bin/ngcp-fraud-notifier
+++ b/bin/ngcp-fraud-notifier
@@ -18,9 +18,9 @@ use File::Pid;
 Readonly my @required => qw();
 Readonly my $config_file => '/etc/ngcp-panel/provisioning.conf';
 
-my $PROGRAM_BASE = "ngcp-fraud-notifier";
+my $PROGRAM_BASE = 'ngcp-fraud-notifier';
 my $retcode = 0;
-my $piddir  = "/run/ngcp-fraud-notifier";
+my $piddir  = '/run/ngcp-fraud-notifier';
 my $pidfile = "$piddir/ngcp-fraud-notifier.pid";
 my $pf      =  File::Pid->new({ file => $pidfile });
 
@@ -38,8 +38,8 @@ my $opts = {
 my $config;
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "verbose",
+    'help|h' => sub { usage() },
+    'verbose',
 ) or usage();
 
 sub DESTROY {
@@ -190,7 +190,7 @@ sub update_notify_status {
                  { op => 'replace',
                    path => '/notified_at',
                    value => $now } ];
-    my $res = $client->request("PATCH", $uri, $data);
+    my $res = $client->request('PATCH', $uri, $data);
 
     return;
 }
diff --git a/bin/ngcp-get-customer b/bin/ngcp-get-customer
index df1ba88..6f6f546 100755
--- a/bin/ngcp-get-customer
+++ b/bin/ngcp-get-customer
@@ -14,9 +14,9 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "customer_id=i",
-    "verbose",
+    'help|h' => sub { usage() },
+    'customer_id=i',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -45,7 +45,7 @@ sub main {
 
     my $uri = '/api/customers/';
     $uri .= $opts->{customer_id} ? $opts->{customer_id} : '';
-    my $res = $client->request("GET", $uri);
+    my $res = $client->request('GET', $uri);
     $res->is_success ? print $res->decoded_content."\n"
                      : print $res->result."\n";
 
diff --git a/bin/ngcp-sound-set b/bin/ngcp-sound-set
index b242a77..9b0b643 100755
--- a/bin/ngcp-sound-set
+++ b/bin/ngcp-sound-set
@@ -14,9 +14,9 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "id=i",
-    "verbose",
+    'help|h' => sub { usage() },
+    'id=i',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -45,7 +45,7 @@ sub main {
 
     my $uri = '/api/soundsets/';
     $uri .= $opts->{id} ? $opts->{id} : '';
-    my $res = $client->request("GET", $uri);
+    my $res = $client->request('GET', $uri);
     $res->is_success ? print $res->content."\n"
                      : print $res->result."\n";
 
diff --git a/bin/ngcp-terminate-customer b/bin/ngcp-terminate-customer
index 9118c3a..fc1d1c5 100755
--- a/bin/ngcp-terminate-customer
+++ b/bin/ngcp-terminate-customer
@@ -14,9 +14,9 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "customer_id=i",
-    "verbose",
+    'help|h' => sub { usage() },
+    'customer_id=i',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -47,7 +47,7 @@ sub main {
     my $data = [ { op => 'replace',
                    path => '/status',
                    value => 'terminated' } ];
-    my $res = $client->request("PATCH", $uri, $data);
+    my $res = $client->request('PATCH', $uri, $data);
     print $res->result."\n";
 
     return !$res->is_success;
diff --git a/bin/ngcp-terminate-subscriber b/bin/ngcp-terminate-subscriber
index 20c122e..e0d59d1 100755
--- a/bin/ngcp-terminate-subscriber
+++ b/bin/ngcp-terminate-subscriber
@@ -14,10 +14,10 @@ my $opts = {
 };
 
 GetOptions( $opts,
-    "help|h" => sub { usage() },
-    "username=s",
-    "domain=s",
-    "verbose",
+    'help|h' => sub { usage() },
+    'username=s',
+    'domain=s',
+    'verbose',
 ) or usage();
 
 sub check_params {
@@ -46,7 +46,8 @@ sub main {
 
     my $uri = sprintf '/api/subscribers/?username=%s&domain=%s',
               @{$opts}{qw(username domain)};
-    my $sub = $client->request("GET", $uri);
+    my $sub = $client->request('GET', $uri);
+
     my $sub_id;
     if ($sub->as_hash->{total_count} == 1) {
         my $tmp = $sub->as_hash->{_embedded}->{'ngcp:subscribers'};
@@ -63,7 +64,7 @@ sub main {
     my $data = [ { op => 'replace',
                    path => '/status',
                    value => 'terminated' } ];
-    my $res = $client->request("PATCH", $uri, $data);
+    my $res = $client->request('PATCH', $uri, $data);
     print $res->result."\n";
 
     return !$res->is_success;
diff --git a/lib/NGCP/API/Client.pm b/lib/NGCP/API/Client.pm
index ba7ccfe..9fe3a8d 100644
--- a/lib/NGCP/API/Client.pm
+++ b/lib/NGCP/API/Client.pm
@@ -237,7 +237,7 @@ sub result {
         $content = $self->content;
     }
 
-    return sprintf "%s %s", $self->status_line, $content;
+    return sprintf '%s %s', $self->status_line, $content;
 }
 
 1;
@@ -305,7 +305,7 @@ The version is compatible with NGCP platforms version >= mr4.3.x
             value => 5,
         },
     ];
-    my $res = $client->request("PATCH", $uri, $data);
+    my $res = $client->request('PATCH', $uri, $data);
 
     # DELETE (remove)