diff --git a/composer.json b/composer.json
index eaa8e87b..3fbc7cec 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
         "psr-4": { "Leafo\\ScssPhp\\Test\\": "tests/" }
     },
     "require": {
-        "php": "^5.4.0 || ^7"
+        "php": "^5.4.0 || ^7 || ^8.0"
     },
     "require-dev": {
         "squizlabs/php_codesniffer": "~2.5",
diff --git a/src/Compiler.php b/src/Compiler.php
index d22d0a35..2fefccc1 100644
--- a/src/Compiler.php
+++ b/src/Compiler.php
@@ -2552,8 +2552,8 @@ protected function shouldEval($value)
      */
     protected function reduce($value, $inExp = false)
     {
-
-        switch ($value[0]) {
+        $switch = !empty($value) ? $value[0] : null;
+        switch ($switch) {
             case Type::T_EXPRESSION:
                 list(, $op, $left, $right, $inParens) = $value;
 
@@ -4373,7 +4373,7 @@ protected function sortArgs($prototype, $args)
         foreach ($args as $arg) {
             list($key, $value) = $arg;
 
-            $key = $key[1];
+            $key = isset($key[1]) ? $key[1] : '';
 
             if (empty($key)) {
                 $posArgs[] = empty($arg[2]) ? $value : $arg;
@@ -5889,7 +5889,7 @@ protected function libStrSlice($args)
             $start--;
         }
 
-        $end    = (int) $args[2][1];
+        $end    = (isset($args[2][1]) ? (int) $args[2][1] : 0);
         $length = $end < 0 ? $end + 1 : ($end > 0 ? $end - $start : $end);
 
         $string[2] = $length