diff --git a/docker/settings.php b/docker/settings.php
index 4aacdc2..34bd285 100644
--- a/docker/settings.php
+++ b/docker/settings.php
@@ -4,18 +4,18 @@
 	$settings = [
 		"site_title" => getenv('SITE_TITLE') ?: "FlashPaper :: Self-Destructing Message",
 		"site_logo" => getenv('SITE_LOGO') ?: "img/logo.svg",
-		"display_logo" => getenv('DISPLAY_LOGO') ?: "true",
-		"display_title" => getenv('DISPLAY_TITLE') ?: "false",
-		"custom_css" => getenv('CUSTOM_CSS') ?: "false",
+		"display_logo" => filter_var(getenv('DISPLAY_LOGO') ?: "true", FILTER_VALIDATE_BOOLEAN),
+		"display_title" => filter_var(getenv('DISPLAY_TITLE') ?: "false", FILTER_VALIDATE_BOOLEAN),
+		"custom_css" => filter_var(getenv('CUSTOM_CSS') ?: "false", FILTER_VALIDATE_BOOLEAN),
 		"bootstrap_theme" => getenv('BOOTSTRAP_THEME') ?: "flashpaper",
-		"return_full_url" => getenv('RETURN_FULL_URL') ?: "true",
+		"return_full_url" => filter_var(getenv('RETURN_FULL_URL') ?: "true", FILTER_VALIDATE_BOOLEAN),
 		"base_url" => getenv('BASE_URL') ?: "",
-		"max_secret_length" => getenv('MAX_SECRET_LENGTH') ?: 3000,
+		"max_secret_length" => (int)(getenv('MAX_SECRET_LENGTH') ?: 3000),
 		"announcement" => getenv('ANNOUNCEMENT') ?: "",
 		'prune' => [
-			'enabled' => getenv('PRUNE_ENABLED') ?: "true",
-			'min_days' => getenv('PRUNE_MIN_DAYS') ?: 365,
-			'max_days' => getenv('PRUNE_MAX_DAYS') ?: 730,
+			'enabled' => filter_var(getenv('PRUNE_ENABLED') ?: "true", FILTER_VALIDATE_BOOLEAN),
+			'min_days' => (int)(getenv('PRUNE_MIN_DAYS') ?: 365),
+			'max_days' => (int)(getenv('PRUNE_MAX_DAYS') ?: 730),
 		],
 		"messages" => [
 			"error_secret_too_long" => getenv('MESSAGES_ERROR_SECRET_TOO_LONG') ?: "Input length too long",