diff --git a/composer/composer/InstalledVersions.php b/composer/composer/InstalledVersions.php
index c6b54af7ba2..51e734a774b 100644
--- a/composer/composer/InstalledVersions.php
+++ b/composer/composer/InstalledVersions.php
@@ -98,7 +98,7 @@ public static function isInstalled($packageName, $includeDevRequirements = true)
     {
         foreach (self::getInstalled() as $installed) {
             if (isset($installed['versions'][$packageName])) {
-                return $includeDevRequirements || empty($installed['versions'][$packageName]['dev_requirement']);
+                return $includeDevRequirements || !isset($installed['versions'][$packageName]['dev_requirement']) || $installed['versions'][$packageName]['dev_requirement'] === false;
             }
         }
 
@@ -119,7 +119,7 @@ public static function isInstalled($packageName, $includeDevRequirements = true)
      */
     public static function satisfies(VersionParser $parser, $packageName, $constraint)
     {
-        $constraint = $parser->parseConstraints($constraint);
+        $constraint = $parser->parseConstraints((string) $constraint);
         $provided = $parser->parseConstraints(self::getVersionRanges($packageName));
 
         return $provided->matches($constraint);
@@ -328,7 +328,9 @@ private static function getInstalled()
                 if (isset(self::$installedByVendor[$vendorDir])) {
                     $installed[] = self::$installedByVendor[$vendorDir];
                 } elseif (is_file($vendorDir.'/composer/installed.php')) {
-                    $installed[] = self::$installedByVendor[$vendorDir] = require $vendorDir.'/composer/installed.php';
+                    /** @var array{root: array{name: string, pretty_version: string, version: string, reference: string|null, type: string, install_path: string, aliases: string[], dev: bool}, versions: array<string, array{pretty_version?: string, version?: string, reference?: string|null, type?: string, install_path?: string, aliases?: string[], dev_requirement: bool, replaced?: string[], provided?: string[]}>} $required */
+                    $required = require $vendorDir.'/composer/installed.php';
+                    $installed[] = self::$installedByVendor[$vendorDir] = $required;
                     if (null === self::$installed && strtr($vendorDir.'/composer', '\\', '/') === strtr(__DIR__, '\\', '/')) {
                         self::$installed = $installed[count($installed) - 1];
                     }
@@ -340,12 +342,17 @@ private static function getInstalled()
             // only require the installed.php file if this file is loaded from its dumped location,
             // and not from its source location in the composer/composer package, see https://github.com/composer/composer/issues/9937
             if (substr(__DIR__, -8, 1) !== 'C') {
-                self::$installed = require __DIR__ . '/installed.php';
+                /** @var array{root: array{name: string, pretty_version: string, version: string, reference: string|null, type: string, install_path: string, aliases: string[], dev: bool}, versions: array<string, array{pretty_version?: string, version?: string, reference?: string|null, type?: string, install_path?: string, aliases?: string[], dev_requirement: bool, replaced?: string[], provided?: string[]}>} $required */
+                $required = require __DIR__ . '/installed.php';
+                self::$installed = $required;
             } else {
                 self::$installed = array();
             }
         }
-        $installed[] = self::$installed;
+
+        if (self::$installed !== array()) {
+            $installed[] = self::$installed;
+        }
 
         return $installed;
     }
diff --git a/composer/composer/installed.php b/composer/composer/installed.php
index a07a8bb44ce..47c190be46a 100644
--- a/composer/composer/installed.php
+++ b/composer/composer/installed.php
@@ -1,9 +1,9 @@
 <?php return array(
     'root' => array(
         'name' => '__root__',
-        'pretty_version' => 'dev-master',
-        'version' => 'dev-master',
-        'reference' => 'fdbb588098d7634f7fe7bffb4eaeaf75563f1b18',
+        'pretty_version' => 'dev-main',
+        'version' => 'dev-main',
+        'reference' => '00b8b908ec601f3541533afb5f8addc06038423e',
         'type' => 'library',
         'install_path' => __DIR__ . '/../',
         'aliases' => array(),
@@ -11,9 +11,9 @@
     ),
     'versions' => array(
         '__root__' => array(
-            'pretty_version' => 'dev-master',
-            'version' => 'dev-master',
-            'reference' => 'fdbb588098d7634f7fe7bffb4eaeaf75563f1b18',
+            'pretty_version' => 'dev-main',
+            'version' => 'dev-main',
+            'reference' => '00b8b908ec601f3541533afb5f8addc06038423e',
             'type' => 'library',
             'install_path' => __DIR__ . '/../',
             'aliases' => array(),