diff --git a/src/Composer/Package/Locker.php b/src/Composer/Package/Locker.php
index a78c2ccde..b7eba4b99 100644
--- a/src/Composer/Package/Locker.php
+++ b/src/Composer/Package/Locker.php
@@ -298,6 +298,8 @@ class Locker
                 }
             }
 
+            unset($spec['installation-source']);
+
             $locked[] = $spec;
         }