diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index b9508107..edf01645 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -15,6 +15,7 @@
         'array_syntax' => ['syntax' => 'short'],
         'combine_consecutive_unsets' => true,
         'concat_space' => [ 'spacing' => 'one'],
+        'declare_strict_types' => true,
         'explicit_string_variable' => false,
         'fopen_flags' => ['b_mode' => true],
         'heredoc_to_nowdoc' => true,
diff --git a/dev-bin/phar-test.php b/dev-bin/phar-test.php
index a355ecd2..9c2aab37 100755
--- a/dev-bin/phar-test.php
+++ b/dev-bin/phar-test.php
@@ -1,6 +1,8 @@
 #!/usr/bin/env php
 <?php
 
+declare(strict_types=1);
+
 require_once 'geoip2.phar';
 use GeoIp2\Database\Reader;
 
diff --git a/examples/benchmark.php b/examples/benchmark.php
index eb657d6f..ccdfc3d7 100644
--- a/examples/benchmark.php
+++ b/examples/benchmark.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 require __DIR__ . '/../vendor/autoload.php';
 
 use GeoIp2\Database\Reader;