diff --git a/composer.json b/composer.json
index 9fbe22c3d..66e150798 100644
--- a/composer.json
+++ b/composer.json
@@ -21,6 +21,9 @@
         "symfony/phpunit-bridge": "^4.4.12|^5.0|^6.0",
         "symfony/process": "^4.4|^5.0|^6.0"
     },
+    "conflict": {
+        "composer/semver": "<1.7.2"
+    },
     "autoload": {
         "psr-4": {
             "Symfony\\Flex\\": "src"
diff --git a/src/Flex.php b/src/Flex.php
index a45ce90df..30be50649 100644
--- a/src/Flex.php
+++ b/src/Flex.php
@@ -391,6 +391,10 @@ public function recordOperations(InstallerEvent $event)
         $versionParser = new VersionParser();
         $packages = [];
         foreach ($this->lock->all() as $name => $info) {
+            if ('9999999.9999999' === $info['version']) {
+                // Fix invalid versions found in some lock files
+                $info['version'] = '99999.9999999';
+            }
             $packages[] = new Package($name, $versionParser->normalize($info['version']), $info['version']);
         }