diff --git a/tpl/bootstrap.php b/tpl/bootstrap.php
index 901bced7..3cc2331c 100644
--- a/tpl/bootstrap.php
+++ b/tpl/bootstrap.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 use PrivateBin\I18n;
 $isCpct = substr($template, 9, 8) === '-compact';
 $isDark = substr($template, 9, 5) === '-dark';
diff --git a/tpl/bootstrap5.php b/tpl/bootstrap5.php
index 298c1684..f3bfe55f 100644
--- a/tpl/bootstrap5.php
+++ b/tpl/bootstrap5.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 use PrivateBin\I18n;
 ?><!DOCTYPE html>
 <html lang="<?php echo I18n::getLanguage(); ?>"<?php echo I18n::isRtl() ? ' dir="rtl"' : ''; ?>>
diff --git a/tpl/page.php b/tpl/page.php
index 299e877b..ffe0a2cd 100644
--- a/tpl/page.php
+++ b/tpl/page.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 use PrivateBin\I18n;
 ?><!DOCTYPE html>
 <html lang="<?php echo I18n::getLanguage(); ?>"<?php echo I18n::isRtl() ? ' dir="rtl"' : ''; ?>>
diff --git a/tpl/yourlsproxy.php b/tpl/yourlsproxy.php
index fc56ba82..bb63d6ce 100644
--- a/tpl/yourlsproxy.php
+++ b/tpl/yourlsproxy.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 use PrivateBin\I18n;
 ?><!DOCTYPE html>
 <html lang="<?php echo I18n::getLanguage(); ?>"<?php echo I18n::isRtl() ? ' dir="rtl"' : ''; ?>>
