diff --git a/phpBB/phpbb/template/base.php b/phpBB/phpbb/template/base.php
index 314cdc4796..2cc71869aa 100644
--- a/phpBB/phpbb/template/base.php
+++ b/phpBB/phpbb/template/base.php
@@ -87,7 +87,7 @@ abstract class base implements template
 	/**
 	* {@inheritdoc}
 	*/
-	public function assign_var($varname, $varval)
+	public function assign_var(string $varname, mixed $varval)
 	{
 		$this->context->assign_var($varname, $varval);
 
diff --git a/phpBB/phpbb/template/context.php b/phpBB/phpbb/template/context.php
index b510c88ad5..d952a84334 100644
--- a/phpBB/phpbb/template/context.php
+++ b/phpBB/phpbb/template/context.php
@@ -60,10 +60,10 @@ class context
 	* Value can be a string, an integer or a boolean.
 	*
 	* @param string $varname Variable name
-	* @param bool|int|string $varval Value to assign to variable
+	* @param mixed $varval Value to assign to variable
 	* @return true
 	*/
-	public function assign_var(string $varname, bool|int|string $varval)
+	public function assign_var(string $varname, mixed $varval)
 	{
 		$this->rootref[$varname] = $varval;
 
diff --git a/phpBB/phpbb/template/template.php b/phpBB/phpbb/template/template.php
index c251513698..fef35de0c3 100644
--- a/phpBB/phpbb/template/template.php
+++ b/phpBB/phpbb/template/template.php
@@ -103,10 +103,10 @@ interface template
 	* Value can be a string, an integer or a boolean.
 	*
 	* @param string $varname Variable name
-	* @param bool|int|string $varval Value to assign to variable
+	* @param mixed $varval Value to assign to variable
 	* @return \phpbb\template\template $this
 	*/
-	public function assign_var(string $varname, bool|int|string $varval);
+	public function assign_var(string $varname, mixed $varval);
 
 	/**
 	* Append text to the string value stored in a key.