diff --git a/src/Composer/Package/BasePackage.php b/src/Composer/Package/BasePackage.php
index f6b800ea7..f02c0ee40 100644
--- a/src/Composer/Package/BasePackage.php
+++ b/src/Composer/Package/BasePackage.php
@@ -149,7 +149,7 @@ abstract class BasePackage implements PackageInterface
      */
     public static function parseVersion($version)
     {
-        if (!preg_match('#^v?(\d+)(\.\d+)?(\.\d+)?-?((?:beta|RC\d+|alpha)\d*)?-?(dev)?$#i', $version, $matches)) {
+        if (!preg_match('#^v?(\d+)(\.\d+)?(\.\d+)?-?((?:beta|RC|alpha)\d*)?-?(dev)?$#i', $version, $matches)) {
             throw new \UnexpectedValueException('Invalid version string '.$version);
         }