diff --git a/modules/notification/base/notifier.go b/modules/notification/base/notifier.go
index c74bb52014..b0e7b4cae8 100644
--- a/modules/notification/base/notifier.go
+++ b/modules/notification/base/notifier.go
@@ -20,7 +20,7 @@ type Notifier interface {
 
 	NotifyNewIssue(*models.Issue)
 	NotifyIssueChangeStatus(*models.User, *models.Issue, bool)
-	NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue)
+	NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue, oldMilestoneID int64)
 	NotifyIssueChangeAssignee(doer *models.User, issue *models.Issue, assignee *models.User, removed bool, comment *models.Comment)
 	NotifyIssueChangeContent(doer *models.User, issue *models.Issue, oldContent string)
 	NotifyIssueClearLabels(doer *models.User, issue *models.Issue)
diff --git a/modules/notification/base/null.go b/modules/notification/base/null.go
index 9fb08884a1..3524a53c15 100644
--- a/modules/notification/base/null.go
+++ b/modules/notification/base/null.go
@@ -75,7 +75,7 @@ func (*NullNotifier) NotifyDeleteRelease(doer *models.User, rel *models.Release)
 }
 
 // NotifyIssueChangeMilestone places a place holder function
-func (*NullNotifier) NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue) {
+func (*NullNotifier) NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue, oldMilestoneID int64) {
 }
 
 // NotifyIssueChangeContent places a place holder function
diff --git a/modules/notification/notification.go b/modules/notification/notification.go
index 0f1b63cf67..70b1541e35 100644
--- a/modules/notification/notification.go
+++ b/modules/notification/notification.go
@@ -128,9 +128,9 @@ func NotifyDeleteRelease(doer *models.User, rel *models.Release) {
 }
 
 // NotifyIssueChangeMilestone notifies change milestone to notifiers
-func NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue) {
+func NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue, oldMilestoneID int64) {
 	for _, notifier := range notifiers {
-		notifier.NotifyIssueChangeMilestone(doer, issue)
+		notifier.NotifyIssueChangeMilestone(doer, issue, oldMilestoneID)
 	}
 }
 
diff --git a/modules/notification/webhook/webhook.go b/modules/notification/webhook/webhook.go
index 259b6352ab..a969ad74f7 100644
--- a/modules/notification/webhook/webhook.go
+++ b/modules/notification/webhook/webhook.go
@@ -419,3 +419,45 @@ func (m *webhookNotifier) NotifyIssueChangeLabels(doer *models.User, issue *mode
 		log.Error("PrepareWebhooks [is_pull: %v]: %v", issue.IsPull, err)
 	}
 }
+
+func (m *webhookNotifier) NotifyIssueChangeMilestone(doer *models.User, issue *models.Issue, oldMilestoneID int64) {
+	var hookAction api.HookIssueAction
+	var err error
+	if issue.MilestoneID > 0 {
+		hookAction = api.HookIssueMilestoned
+	} else {
+		hookAction = api.HookIssueDemilestoned
+	}
+
+	if err = issue.LoadAttributes(); err != nil {
+		log.Error("issue.LoadAttributes failed: %v", err)
+		return
+	}
+
+	mode, _ := models.AccessLevel(doer, issue.Repo)
+	if issue.IsPull {
+		err = issue.PullRequest.LoadIssue()
+		if err != nil {
+			log.Error("LoadIssue: %v", err)
+			return
+		}
+		err = webhook_module.PrepareWebhooks(issue.Repo, models.HookEventPullRequest, &api.PullRequestPayload{
+			Action:      hookAction,
+			Index:       issue.Index,
+			PullRequest: issue.PullRequest.APIFormat(),
+			Repository:  issue.Repo.APIFormat(mode),
+			Sender:      doer.APIFormat(),
+		})
+	} else {
+		err = webhook_module.PrepareWebhooks(issue.Repo, models.HookEventIssues, &api.IssuePayload{
+			Action:     hookAction,
+			Index:      issue.Index,
+			Issue:      issue.APIFormat(),
+			Repository: issue.Repo.APIFormat(mode),
+			Sender:     doer.APIFormat(),
+		})
+	}
+	if err != nil {
+		log.Error("PrepareWebhooks [is_pull: %v]: %v", issue.IsPull, err)
+	}
+}
diff --git a/routers/api/v1/repo/issue.go b/routers/api/v1/repo/issue.go
index fe5862ea5e..1534c45df0 100644
--- a/routers/api/v1/repo/issue.go
+++ b/routers/api/v1/repo/issue.go
@@ -20,7 +20,6 @@ import (
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
 	issue_service "code.gitea.io/gitea/services/issue"
-	milestone_service "code.gitea.io/gitea/services/milestone"
 )
 
 // SearchIssues searches for issues across the repositories that the user has access to
@@ -494,7 +493,7 @@ func EditIssue(ctx *context.APIContext, form api.EditIssueOption) {
 		issue.MilestoneID != *form.Milestone {
 		oldMilestoneID := issue.MilestoneID
 		issue.MilestoneID = *form.Milestone
-		if err = milestone_service.ChangeMilestoneAssign(issue, ctx.User, oldMilestoneID); err != nil {
+		if err = issue_service.ChangeMilestoneAssign(issue, ctx.User, oldMilestoneID); err != nil {
 			ctx.Error(500, "ChangeMilestoneAssign", err)
 			return
 		}
diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index 0180aebf89..9264c00cec 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -18,7 +18,6 @@ import (
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/timeutil"
 	issue_service "code.gitea.io/gitea/services/issue"
-	milestone_service "code.gitea.io/gitea/services/milestone"
 	pull_service "code.gitea.io/gitea/services/pull"
 )
 
@@ -420,7 +419,7 @@ func EditPullRequest(ctx *context.APIContext, form api.EditPullRequestOption) {
 		issue.MilestoneID != form.Milestone {
 		oldMilestoneID := issue.MilestoneID
 		issue.MilestoneID = form.Milestone
-		if err = milestone_service.ChangeMilestoneAssign(issue, ctx.User, oldMilestoneID); err != nil {
+		if err = issue_service.ChangeMilestoneAssign(issue, ctx.User, oldMilestoneID); err != nil {
 			ctx.Error(500, "ChangeMilestoneAssign", err)
 			return
 		}
diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index 9a691471d5..739370da69 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -28,7 +28,6 @@ import (
 	"code.gitea.io/gitea/modules/util"
 	comment_service "code.gitea.io/gitea/services/comments"
 	issue_service "code.gitea.io/gitea/services/issue"
-	milestone_service "code.gitea.io/gitea/services/milestone"
 
 	"github.com/unknwon/com"
 )
@@ -1099,7 +1098,7 @@ func UpdateIssueMilestone(ctx *context.Context) {
 			continue
 		}
 		issue.MilestoneID = milestoneID
-		if err := milestone_service.ChangeMilestoneAssign(issue, ctx.User, oldMilestoneID); err != nil {
+		if err := issue_service.ChangeMilestoneAssign(issue, ctx.User, oldMilestoneID); err != nil {
 			ctx.ServerError("ChangeMilestoneAssign", err)
 			return
 		}
diff --git a/services/issue/milestone.go b/services/issue/milestone.go
new file mode 100644
index 0000000000..6fe527f58c
--- /dev/null
+++ b/services/issue/milestone.go
@@ -0,0 +1,21 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package issue
+
+import (
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/notification"
+)
+
+// ChangeMilestoneAssign changes assignment of milestone for issue.
+func ChangeMilestoneAssign(issue *models.Issue, doer *models.User, oldMilestoneID int64) (err error) {
+	if err = models.ChangeMilestoneAssign(issue, doer, oldMilestoneID); err != nil {
+		return
+	}
+
+	notification.NotifyIssueChangeMilestone(doer, issue, oldMilestoneID)
+
+	return nil
+}
diff --git a/services/milestone/milestone.go b/services/milestone/milestone.go
deleted file mode 100644
index 84e7fb30e2..0000000000
--- a/services/milestone/milestone.go
+++ /dev/null
@@ -1,58 +0,0 @@
-// Copyright 2019 The Gitea Authors. All rights reserved.
-// Use of this source code is governed by a MIT-style
-// license that can be found in the LICENSE file.
-
-package models
-
-import (
-	"code.gitea.io/gitea/models"
-	"code.gitea.io/gitea/modules/log"
-	api "code.gitea.io/gitea/modules/structs"
-	"code.gitea.io/gitea/modules/webhook"
-)
-
-// ChangeMilestoneAssign changes assignment of milestone for issue.
-func ChangeMilestoneAssign(issue *models.Issue, doer *models.User, oldMilestoneID int64) (err error) {
-	if err = models.ChangeMilestoneAssign(issue, doer, oldMilestoneID); err != nil {
-		return
-	}
-
-	var hookAction api.HookIssueAction
-	if issue.MilestoneID > 0 {
-		hookAction = api.HookIssueMilestoned
-	} else {
-		hookAction = api.HookIssueDemilestoned
-	}
-
-	if err = issue.LoadAttributes(); err != nil {
-		return err
-	}
-
-	mode, _ := models.AccessLevel(doer, issue.Repo)
-	if issue.IsPull {
-		err = issue.PullRequest.LoadIssue()
-		if err != nil {
-			log.Error("LoadIssue: %v", err)
-			return
-		}
-		err = webhook.PrepareWebhooks(issue.Repo, models.HookEventPullRequest, &api.PullRequestPayload{
-			Action:      hookAction,
-			Index:       issue.Index,
-			PullRequest: issue.PullRequest.APIFormat(),
-			Repository:  issue.Repo.APIFormat(mode),
-			Sender:      doer.APIFormat(),
-		})
-	} else {
-		err = webhook.PrepareWebhooks(issue.Repo, models.HookEventIssues, &api.IssuePayload{
-			Action:     hookAction,
-			Index:      issue.Index,
-			Issue:      issue.APIFormat(),
-			Repository: issue.Repo.APIFormat(mode),
-			Sender:     doer.APIFormat(),
-		})
-	}
-	if err != nil {
-		log.Error("PrepareWebhooks [is_pull: %v]: %v", issue.IsPull, err)
-	}
-	return nil
-}