diff --git a/src/Composer/Package/RootPackageInterface.php b/src/Composer/Package/RootPackageInterface.php
index 7bee86324..7d39ff7bc 100644
--- a/src/Composer/Package/RootPackageInterface.php
+++ b/src/Composer/Package/RootPackageInterface.php
@@ -20,7 +20,7 @@ namespace Composer\Package;
 interface RootPackageInterface extends CompletePackageInterface
 {
     /**
-     * Returns a set of package names and theirs aliases
+     * Returns a set of package names and their aliases
      *
      * @return array
      */