diff --git a/src/Discovery/BundleDiscovery.php b/src/Discovery/BundleDiscovery.php
index 503e196..1cf8c9c 100644
--- a/src/Discovery/BundleDiscovery.php
+++ b/src/Discovery/BundleDiscovery.php
@@ -126,7 +126,7 @@ private function composerBundle(string $packageName): ?BundleMetadata
 
         $composerFile = sprintf('%s/composer.json', $installPath);
 
-        if (!is_file($composerFile)) {
+        if (!$this->knownComposerFile($composerFile)) {
             return null;
         }
 
@@ -457,7 +457,7 @@ private function requirementsActive(array $requirements): bool
 
             $composerFile = sprintf('%s/composer.json', $installPath);
 
-            if (!is_file($composerFile)) {
+            if (!$this->knownComposerFile($composerFile)) {
                 return false;
             }
 
@@ -503,6 +503,15 @@ private function kernelRequirements(mixed $kernel): array
         );
     }
 
+    /**
+     * Metadata restored from the manifest cache was validated against the file's
+     * fingerprint already; only unknown files need a filesystem probe.
+     */
+    private function knownComposerFile(string $composerFile): bool
+    {
+        return isset($this->metadata[$composerFile]) || is_file($composerFile);
+    }
+
     /** @return array<string, mixed> */
     private function composerMetadata(string $composerFile): array
     {