diff --git a/Dotenv.php b/Dotenv.php
index c8a4737..bbc5d04 100644
--- a/Dotenv.php
+++ b/Dotenv.php
@@ -36,8 +36,12 @@ final class Dotenv
     private string $data;
     private int $end;
     private array $values = [];
+    private array $overriddenValues = [];
+    private array $loadedRawVars = [];
     private array $prodEnvs = ['prod'];
     private bool $usePutenv = false;
+    private bool $deferPutenv = false;
+    private array $pendingPutenv = [];
 
     public function __construct(
         private string $envKey = 'APP_ENV',
@@ -79,8 +83,13 @@ public function usePutenv(bool $usePutenv = true): static
      */
     public function load(string $path, string ...$extraPaths): void
     {
-        $this->doLoad(false, \func_get_args());
-        $this->resolveLoadedVars();
+        $this->deferPutenv = true;
+        try {
+            $this->doLoad(false, \func_get_args());
+            $this->resolveLoadedVars();
+        } finally {
+            $this->deferPutenv = false;
+        }
     }
 
     /**
@@ -102,6 +111,7 @@ public function loadEnv(string $path, ?string $envKey = null, string $defaultEnv
     {
         $this->populatePath($path);
 
+        $this->deferPutenv = true;
         try {
             $k = $envKey ?? $this->envKey;
 
@@ -137,7 +147,11 @@ public function loadEnv(string $path, ?string $envKey = null, string $defaultEnv
                 $this->doLoad($overrideExistingVars, [$p]);
             }
         } finally {
-            $this->resolveLoadedVars();
+            try {
+                $this->resolveLoadedVars();
+            } finally {
+                $this->deferPutenv = false;
+            }
         }
     }
 
@@ -179,8 +193,13 @@ public function bootEnv(string $path, string $defaultEnv = 'dev', array $testEnv
      */
     public function overload(string $path, string ...$extraPaths): void
     {
-        $this->doLoad(true, \func_get_args());
-        $this->resolveLoadedVars();
+        $this->deferPutenv = true;
+        try {
+            $this->doLoad(true, \func_get_args());
+            $this->resolveLoadedVars();
+        } finally {
+            $this->deferPutenv = false;
+        }
     }
 
     /**
@@ -206,7 +225,11 @@ public function populate(array $values, bool $overrideExistingVars = false): voi
             }
 
             if ($this->usePutenv) {
-                putenv("$name=$value");
+                if ($this->deferPutenv) {
+                    $this->pendingPutenv[$name] = true;
+                } else {
+                    putenv("$name=$value");
+                }
             }
 
             $_ENV[$name] = $value;
@@ -643,7 +666,21 @@ private function doLoad(bool $overrideExistingVars, array $paths): void
                 throw new FormatException('Loading files containing NUL bytes is not supported.', new FormatExceptionContext($data, $path, 1, 0));
             }
 
-            $this->populate($this->parseRaw($data, $path), $overrideExistingVars);
+            $values = $this->parseRaw($data, $path);
+
+            $loadedVars = array_flip(explode(',', $_SERVER['SYMFONY_DOTENV_VARS'] ?? $_ENV['SYMFONY_DOTENV_VARS'] ?? ''));
+            unset($loadedVars['']);
+
+            foreach ($values as $name => $_) {
+                if (!isset($this->overriddenValues[$name]) && isset($_ENV[$name])) {
+                    $this->overriddenValues[$name] = $_ENV[$name];
+                }
+                if (isset($loadedVars[$name]) || $overrideExistingVars || !isset($_ENV[$name])) {
+                    $this->loadedRawVars[$name] = true;
+                }
+            }
+
+            $this->populate($values, $overrideExistingVars);
         }
     }
 
@@ -696,6 +733,10 @@ private function resolveLoadedVars(): void
         $loadedVars = array_flip(explode(',', $_SERVER['SYMFONY_DOTENV_VARS'] ?? $_ENV['SYMFONY_DOTENV_VARS'] ?? ''));
         unset($loadedVars['']);
 
+        $rawVars = $this->loadedRawVars;
+        $this->loadedRawVars = [];
+        unset($rawVars['SYMFONY_DOTENV_VARS']);
+
         $this->values = [];
         $this->path = '';
         $this->data = '';
@@ -707,10 +748,7 @@ private function resolveLoadedVars(): void
         // (e.g. MY_VAR="${MY_VAR:-default}") so their own raw value is hidden
         // during resolution, allowing the default to trigger correctly.
         $selfReferencingVars = [];
-        foreach ($loadedVars as $name => $_) {
-            if ('SYMFONY_DOTENV_VARS' === $name) {
-                continue;
-            }
+        foreach ($rawVars as $name => $_) {
             $value = $_ENV[$name] ?? '';
             if (str_contains($value, '$') && preg_match('/\$\{?'.preg_quote($name, '/').'(?![A-Za-z0-9_])/', $value)) {
                 $selfReferencingVars[$name] = true;
@@ -719,10 +757,7 @@ private function resolveLoadedVars(): void
 
         for ($pass = 0; $pass < 5; ++$pass) {
             $resolved = [];
-            foreach ($loadedVars as $name => $_) {
-                if ('SYMFONY_DOTENV_VARS' === $name) {
-                    continue;
-                }
+            foreach ($rawVars as $name => $_) {
                 if (!str_contains($value = $_ENV[$name] ?? '', '$')) {
                     continue;
                 }
@@ -730,10 +765,19 @@ private function resolveLoadedVars(): void
                 if (isset($selfReferencingVars[$name])) {
                     $envBackup = $_ENV[$name] ?? null;
                     $serverBackup = $_SERVER[$name] ?? null;
-                    unset($_ENV[$name], $_SERVER[$name]);
+                    if (isset($this->overriddenValues[$name])) {
+                        $_ENV[$name] = $this->overriddenValues[$name];
+                        $_SERVER[$name] = $this->overriddenValues[$name];
+                    } else {
+                        unset($_ENV[$name], $_SERVER[$name]);
+                    }
                     if ($this->usePutenv) {
-                        $getenvBackup = $this->usePutenv ? (string) getenv($name) : null;
-                        putenv($name);
+                        $getenvBackup = (string) getenv($name);
+                        if (isset($this->overriddenValues[$name])) {
+                            putenv("$name={$this->overriddenValues[$name]}");
+                        } else {
+                            putenv($name);
+                        }
                     }
                 }
 
@@ -767,10 +811,7 @@ private function resolveLoadedVars(): void
 
         // Restore literal $ signs and unescape backslashes
         $restored = [];
-        foreach ($loadedVars as $name => $_) {
-            if ('SYMFONY_DOTENV_VARS' === $name) {
-                continue;
-            }
+        foreach ($rawVars as $name => $_) {
             $value = $_ENV[$name] ?? '';
             if ($value !== $newValue = str_replace(["\x00", '\\\\'], ['$', '\\'], $value)) {
                 $restored[$name] = $newValue;
@@ -780,7 +821,15 @@ private function resolveLoadedVars(): void
             $this->populate($restored, true);
         }
 
+        if ($this->usePutenv && $this->pendingPutenv) {
+            foreach ($this->pendingPutenv as $name => $_) {
+                putenv($name.'='.($_ENV[$name] ?? ''));
+            }
+            $this->pendingPutenv = [];
+        }
+
         $this->values = [];
+        $this->overriddenValues = [];
         unset($this->path, $this->data, $this->lineno, $this->cursor, $this->end);
     }
 
@@ -788,7 +837,12 @@ private function populatePath(string $path): void
     {
         $_ENV['SYMFONY_DOTENV_PATH'] = $_SERVER['SYMFONY_DOTENV_PATH'] = $path;
 
-        if ($this->usePutenv) {
+        if (!$this->usePutenv) {
+            return;
+        }
+        if ($this->deferPutenv) {
+            $this->pendingPutenv['SYMFONY_DOTENV_PATH'] = true;
+        } else {
             putenv('SYMFONY_DOTENV_PATH='.$path);
         }
     }
diff --git a/Tests/DotenvTest.php b/Tests/DotenvTest.php
index 8773bb0..66d63d8 100644
--- a/Tests/DotenvTest.php
+++ b/Tests/DotenvTest.php
@@ -235,6 +235,41 @@ public function testLoad()
         $this->assertSame('BAZ', $bar);
     }
 
+    public function testLoadDoesNotReResolveAlreadyLoadedVars()
+    {
+        unset($_ENV['FOO'], $_ENV['BAR'], $_ENV['SYMFONY_DOTENV_VARS']);
+        unset($_SERVER['FOO'], $_SERVER['BAR'], $_SERVER['SYMFONY_DOTENV_VARS']);
+        putenv('FOO');
+        putenv('BAR');
+        putenv('SYMFONY_DOTENV_VARS');
+
+        @mkdir($tmpdir = sys_get_temp_dir().'/dotenv');
+
+        $path1 = tempnam($tmpdir, 'sf-');
+        $path2 = tempnam($tmpdir, 'sf-');
+
+        file_put_contents($path1, "FOO='This\$isokay'");
+        file_put_contents($path2, "BAR='hello'");
+
+        try {
+            (new Dotenv())->load($path1);
+            $this->assertSame('This$isokay', $_ENV['FOO']);
+
+            (new Dotenv())->load($path2);
+            $this->assertSame('This$isokay', $_ENV['FOO']);
+            $this->assertSame('hello', $_ENV['BAR']);
+        } finally {
+            unset($_ENV['FOO'], $_ENV['BAR'], $_ENV['SYMFONY_DOTENV_VARS']);
+            unset($_SERVER['FOO'], $_SERVER['BAR'], $_SERVER['SYMFONY_DOTENV_VARS']);
+            putenv('FOO');
+            putenv('BAR');
+            putenv('SYMFONY_DOTENV_VARS');
+            unlink($path1);
+            unlink($path2);
+            rmdir($tmpdir);
+        }
+    }
+
     public function testLoadEnv()
     {
         $resetContext = static function (): void {
@@ -586,6 +621,60 @@ public function testLoadEnvSelfReferencingVariableWithDefault()
         @rmdir($tmpdir);
     }
 
+    public function testLoadSelfReferencingVariableWithSuffix()
+    {
+        $resetContext = static function (): void {
+            unset($_ENV['SYMFONY_DOTENV_VARS'], $_ENV['MY_VAR']);
+            unset($_SERVER['SYMFONY_DOTENV_VARS'], $_SERVER['MY_VAR']);
+            putenv('SYMFONY_DOTENV_VARS');
+            putenv('MY_VAR');
+        };
+
+        @mkdir($tmpdir = sys_get_temp_dir().'/dotenv');
+        $basePath = tempnam($tmpdir, 'sf-');
+        $overridePath = tempnam($tmpdir, 'sf-');
+
+        // Base file sets original value, override file appends suffix
+        file_put_contents($basePath, 'MY_VAR=original');
+        file_put_contents($overridePath, 'MY_VAR="${MY_VAR}_suffix"');
+
+        $resetContext();
+        $dotenv = (new Dotenv())->usePutenv();
+        $dotenv->load($basePath);
+        $dotenv->load($overridePath);
+
+        $this->assertSame('original_suffix', getenv('MY_VAR'));
+
+        // Test with prefix instead of suffix
+        file_put_contents($overridePath, 'MY_VAR="prefix_${MY_VAR}"');
+
+        $resetContext();
+        $dotenv = (new Dotenv())->usePutenv();
+        $dotenv->load($basePath);
+        $dotenv->load($overridePath);
+
+        $this->assertSame('prefix_original', getenv('MY_VAR'));
+
+        // Test chained loads (three files)
+        $thirdPath = tempnam($tmpdir, 'sf-');
+        file_put_contents($overridePath, 'MY_VAR="${MY_VAR}_middle"');
+        file_put_contents($thirdPath, 'MY_VAR="${MY_VAR}_end"');
+
+        $resetContext();
+        $dotenv = (new Dotenv())->usePutenv();
+        $dotenv->load($basePath);
+        $dotenv->load($overridePath);
+        $dotenv->load($thirdPath);
+
+        $this->assertSame('original_middle_end', getenv('MY_VAR'));
+
+        $resetContext();
+        unlink($basePath);
+        unlink($overridePath);
+        unlink($thirdPath);
+        @rmdir($tmpdir);
+    }
+
     public function testLoadEnvSelfReferencingEnvKeyControlsFileLoading()
     {
         $resetContext = static function (): void {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index fdbf278..758fd35 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/11.5/phpunit.xsd"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/13.1/phpunit.xsd"
          backupGlobals="false"
          colors="true"
          bootstrap="vendor/autoload.php"
@@ -20,7 +20,7 @@
     </testsuites>
 
     <source ignoreSuppressionOfDeprecations="true">
-        <deprecationTrigger>
+        <deprecationTrigger ignoreUndefinedTriggers="true">
             <function>trigger_deprecation</function>
             <method>Doctrine\Deprecations\Deprecation::trigger</method>
             <method>Doctrine\Deprecations\Deprecation::triggerIfCalledFromOutside</method>