diff --git a/Dotenv.php b/Dotenv.php
index 09e847c..57128b4 100644
--- a/Dotenv.php
+++ b/Dotenv.php
@@ -135,7 +135,7 @@ public function populate(array $values, bool $overrideExistingVars = false): voi
         $loadedVars = array_flip(explode(',', $_SERVER['SYMFONY_DOTENV_VARS'] ?? $_ENV['SYMFONY_DOTENV_VARS'] ?? ''));
 
         foreach ($values as $name => $value) {
-            $notHttpName = !str_starts_with($name, 'HTTP_');
+            $notHttpName = 0 !== strpos($name, 'HTTP_');
             // don't check existence with getenv() because of thread safety issues
             if (!isset($loadedVars[$name]) && (!$overrideExistingVars && (isset($_ENV[$name]) || (isset($_SERVER[$name]) && $notHttpName)))) {
                 continue;
@@ -372,7 +372,7 @@ private function skipEmptyLines()
 
     private function resolveCommands(string $value, array $loadedVars): string
     {
-        if (!str_contains($value, '$')) {
+        if (false === strpos($value, '$')) {
             return $value;
         }
 
@@ -408,7 +408,7 @@ private function resolveCommands(string $value, array $loadedVars): string
 
             $env = [];
             foreach ($this->values as $name => $value) {
-                if (isset($loadedVars[$name]) || (!isset($_ENV[$name]) && !(isset($_SERVER[$name]) && !str_starts_with($name, 'HTTP_')))) {
+                if (isset($loadedVars[$name]) || (!isset($_ENV[$name]) && !(isset($_SERVER[$name]) && 0 !== strpos($name, 'HTTP_')))) {
                     $env[$name] = $value;
                 }
             }
@@ -426,7 +426,7 @@ private function resolveCommands(string $value, array $loadedVars): string
 
     private function resolveVariables(string $value, array $loadedVars): string
     {
-        if (!str_contains($value, '$')) {
+        if (false === strpos($value, '$')) {
             return $value;
         }
 
@@ -461,7 +461,7 @@ private function resolveVariables(string $value, array $loadedVars): string
                 $value = $this->values[$name];
             } elseif (isset($_ENV[$name])) {
                 $value = $_ENV[$name];
-            } elseif (isset($_SERVER[$name]) && !str_starts_with($name, 'HTTP_')) {
+            } elseif (isset($_SERVER[$name]) && 0 !== strpos($name, 'HTTP_')) {
                 $value = $_SERVER[$name];
             } elseif (isset($this->values[$name])) {
                 $value = $this->values[$name];
diff --git a/composer.json b/composer.json
index 037d039..a6f7fdd 100644
--- a/composer.json
+++ b/composer.json
@@ -16,8 +16,7 @@
         }
     ],
     "require": {
-        "php": ">=7.1.3",
-        "symfony/polyfill-php80": "^1.16"
+        "php": ">=7.1.3"
     },
     "require-dev": {
         "symfony/process": "^3.4.2|^4.0|^5.0"