diff --git a/src/main/scala/gitbucket/core/controller/MilestonesController.scala b/src/main/scala/gitbucket/core/controller/MilestonesController.scala
index 843aab5..874ebec 100644
--- a/src/main/scala/gitbucket/core/controller/MilestonesController.scala
+++ b/src/main/scala/gitbucket/core/controller/MilestonesController.scala
@@ -98,7 +98,16 @@
       for {
         owner <- params.optionValue("owner")
         repository <- params.optionValue("repository")
-        _ <- getMilestones(owner, repository).find(_.title.equalsIgnoreCase(value))
+        _ <- params.optionValue("milestoneId") match {
+          // existing milestone
+          case Some(id) =>
+            getMilestones(owner, repository)
+              .find(m => m.title.equalsIgnoreCase(value) && m.milestoneId.toString != id)
+          // new milestone
+          case None =>
+            getMilestones(owner, repository)
+              .find(m => m.title.equalsIgnoreCase(value))
+        }
       } yield {
         "Milestone already exists."
       }