diff --git a/models/consistency.go b/models/consistency.go
index 77a8018266e..db5811ccd95 100644
--- a/models/consistency.go
+++ b/models/consistency.go
@@ -141,6 +141,12 @@ func (milestone *Milestone) checkForConsistency(t *testing.T) {
 	actual := getCount(t, x.Where("is_closed=?", true), &Issue{MilestoneID: milestone.ID})
 	assert.EqualValues(t, milestone.NumClosedIssues, actual,
 		"Unexpected number of closed issues for milestone %+v", milestone)
+
+	completeness := 0
+	if milestone.NumIssues > 0 {
+		completeness = milestone.NumClosedIssues * 100 / milestone.NumIssues
+	}
+	assert.Equal(t, completeness, milestone.Completeness)
 }
 
 func (label *Label) checkForConsistency(t *testing.T) {
diff --git a/models/issue.go b/models/issue.go
index 760aaaab096..331ea01fdc1 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -648,8 +648,10 @@ func (issue *Issue) doChangeStatus(e *xorm.Session, doer *User, isMergePull bool
 	}
 
 	// Update issue count of milestone
-	if err := updateMilestoneClosedNum(e, issue.MilestoneID); err != nil {
-		return nil, err
+	if issue.MilestoneID > 0 {
+		if err := updateMilestoneCounters(e, issue.MilestoneID); err != nil {
+			return nil, err
+		}
 	}
 
 	if err := issue.updateClosedNum(e); err != nil {
@@ -912,7 +914,7 @@ func newIssue(e *xorm.Session, doer *User, opts NewIssueOptions) (err error) {
 	opts.Issue.Index = inserted.Index
 
 	if opts.Issue.MilestoneID > 0 {
-		if _, err = e.Exec("UPDATE `milestone` SET num_issues=num_issues+1 WHERE id=?", opts.Issue.MilestoneID); err != nil {
+		if err := updateMilestoneCounters(e, opts.Issue.MilestoneID); err != nil {
 			return err
 		}
 
diff --git a/models/issue_milestone.go b/models/issue_milestone.go
index ec3cbb91dbc..e639b503527 100644
--- a/models/issue_milestone.go
+++ b/models/issue_milestone.go
@@ -129,8 +129,12 @@ func GetMilestoneByRepoIDANDName(repoID int64, name string) (*Milestone, error)
 
 // GetMilestoneByID returns the milestone via id .
 func GetMilestoneByID(id int64) (*Milestone, error) {
+	return getMilestoneByID(x, id)
+}
+
+func getMilestoneByID(e Engine, id int64) (*Milestone, error) {
 	var m Milestone
-	has, err := x.ID(id).Get(&m)
+	has, err := e.ID(id).Get(&m)
 	if err != nil {
 		return nil, err
 	} else if !has {
@@ -155,10 +159,6 @@ func UpdateMilestone(m *Milestone, oldIsClosed bool) error {
 		return err
 	}
 
-	if err := updateMilestoneCompleteness(sess, m.ID); err != nil {
-		return err
-	}
-
 	// if IsClosed changed, update milestone numbers of repository
 	if oldIsClosed != m.IsClosed {
 		if err := updateRepoMilestoneNum(sess, m.RepoID); err != nil {
@@ -171,23 +171,31 @@ func UpdateMilestone(m *Milestone, oldIsClosed bool) error {
 
 func updateMilestone(e Engine, m *Milestone) error {
 	m.Name = strings.TrimSpace(m.Name)
-	_, err := e.ID(m.ID).AllCols().
+	_, err := e.ID(m.ID).AllCols().Update(m)
+	if err != nil {
+		return err
+	}
+	return updateMilestoneCounters(e, m.ID)
+}
+
+// updateMilestoneCounters calculates NumIssues, NumClosesIssues and Completeness
+func updateMilestoneCounters(e Engine, id int64) error {
+	_, err := e.ID(id).
 		SetExpr("num_issues", builder.Select("count(*)").From("issue").Where(
-			builder.Eq{"milestone_id": m.ID},
+			builder.Eq{"milestone_id": id},
 		)).
 		SetExpr("num_closed_issues", builder.Select("count(*)").From("issue").Where(
 			builder.Eq{
-				"milestone_id": m.ID,
+				"milestone_id": id,
 				"is_closed":    true,
 			},
 		)).
-		Update(m)
-	return err
-}
-
-func updateMilestoneCompleteness(e Engine, milestoneID int64) error {
-	_, err := e.Exec("UPDATE `milestone` SET completeness=100*num_closed_issues/(CASE WHEN num_issues > 0 THEN num_issues ELSE 1 END) WHERE id=?",
-		milestoneID,
+		Update(&Milestone{})
+	if err != nil {
+		return err
+	}
+	_, err = e.Exec("UPDATE `milestone` SET completeness=100*num_closed_issues/(CASE WHEN num_issues > 0 THEN num_issues ELSE 1 END) WHERE id=?",
+		id,
 	)
 	return err
 }
@@ -256,25 +264,15 @@ func changeMilestoneAssign(e *xorm.Session, doer *User, issue *Issue, oldMilesto
 	}
 
 	if oldMilestoneID > 0 {
-		if err := updateMilestoneTotalNum(e, oldMilestoneID); err != nil {
+		if err := updateMilestoneCounters(e, oldMilestoneID); err != nil {
 			return err
 		}
-		if issue.IsClosed {
-			if err := updateMilestoneClosedNum(e, oldMilestoneID); err != nil {
-				return err
-			}
-		}
 	}
 
 	if issue.MilestoneID > 0 {
-		if err := updateMilestoneTotalNum(e, issue.MilestoneID); err != nil {
+		if err := updateMilestoneCounters(e, issue.MilestoneID); err != nil {
 			return err
 		}
-		if issue.IsClosed {
-			if err := updateMilestoneClosedNum(e, issue.MilestoneID); err != nil {
-				return err
-			}
-		}
 	}
 
 	if oldMilestoneID > 0 || issue.MilestoneID > 0 {
@@ -558,29 +556,6 @@ func updateRepoMilestoneNum(e Engine, repoID int64) error {
 	return err
 }
 
-func updateMilestoneTotalNum(e Engine, milestoneID int64) (err error) {
-	if _, err = e.Exec("UPDATE `milestone` SET num_issues=(SELECT count(*) FROM issue WHERE milestone_id=?) WHERE id=?",
-		milestoneID,
-		milestoneID,
-	); err != nil {
-		return
-	}
-
-	return updateMilestoneCompleteness(e, milestoneID)
-}
-
-func updateMilestoneClosedNum(e Engine, milestoneID int64) (err error) {
-	if _, err = e.Exec("UPDATE `milestone` SET num_closed_issues=(SELECT count(*) FROM issue WHERE milestone_id=? AND is_closed=?) WHERE id=?",
-		milestoneID,
-		true,
-		milestoneID,
-	); err != nil {
-		return
-	}
-
-	return updateMilestoneCompleteness(e, milestoneID)
-}
-
 //  _____               _            _ _____ _
 // |_   _| __ __ _  ___| | _____  __| |_   _(_)_ __ ___   ___  ___
 //   | || '__/ _` |/ __| |/ / _ \/ _` | | | | | '_ ` _ \ / _ \/ __|
diff --git a/models/issue_milestone_test.go b/models/issue_milestone_test.go
index af264aa2745..5406129884f 100644
--- a/models/issue_milestone_test.go
+++ b/models/issue_milestone_test.go
@@ -215,7 +215,7 @@ func TestChangeMilestoneStatus(t *testing.T) {
 	CheckConsistencyFor(t, &Repository{ID: milestone.RepoID}, &Milestone{})
 }
 
-func TestUpdateMilestoneClosedNum(t *testing.T) {
+func TestUpdateMilestoneCounters(t *testing.T) {
 	assert.NoError(t, PrepareTestDatabase())
 	issue := AssertExistsAndLoadBean(t, &Issue{MilestoneID: 1},
 		"is_closed=0").(*Issue)
@@ -224,14 +224,14 @@ func TestUpdateMilestoneClosedNum(t *testing.T) {
 	issue.ClosedUnix = timeutil.TimeStampNow()
 	_, err := x.ID(issue.ID).Cols("is_closed", "closed_unix").Update(issue)
 	assert.NoError(t, err)
-	assert.NoError(t, updateMilestoneClosedNum(x, issue.MilestoneID))
+	assert.NoError(t, updateMilestoneCounters(x, issue.MilestoneID))
 	CheckConsistencyFor(t, &Milestone{})
 
 	issue.IsClosed = false
 	issue.ClosedUnix = 0
 	_, err = x.ID(issue.ID).Cols("is_closed", "closed_unix").Update(issue)
 	assert.NoError(t, err)
-	assert.NoError(t, updateMilestoneClosedNum(x, issue.MilestoneID))
+	assert.NoError(t, updateMilestoneCounters(x, issue.MilestoneID))
 	CheckConsistencyFor(t, &Milestone{})
 }