diff --git a/entities/profile.go b/entities/profile.go
index d05907a..576d9e2 100644
--- a/entities/profile.go
+++ b/entities/profile.go
@@ -1,6 +1,10 @@
 package entities
 
-import "time"
+import (
+	"time"
+
+	"github.com/Songmu/flextime"
+)
 
 type Profile struct {
 	Job              string    `json:"job"`
@@ -12,5 +16,5 @@ type Profile struct {
 }
 
 func NewProfile(job, description string, skillDescription, licenses []string, pr string) *Profile {
-	return &Profile{job, description, skillDescription, licenses, pr, time.Now()}
+	return &Profile{job, description, skillDescription, licenses, pr, flextime.Now()}
 }
diff --git a/entities/skill.go b/entities/skill.go
index aa00bdf..f9ac1f6 100644
--- a/entities/skill.go
+++ b/entities/skill.go
@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"strings"
 	"time"
+
+	"github.com/Songmu/flextime"
 )
 
 type SkillCategory int
@@ -32,7 +34,7 @@ func NewSkill(name string, lv int, description string, category SkillCategory) *
 		lv,
 		description,
 		category,
-		time.Now(),
+		flextime.Now(),
 	}
 }
 
diff --git a/go.mod b/go.mod
index d051658..cf2f665 100644
--- a/go.mod
+++ b/go.mod
@@ -6,6 +6,7 @@ require (
 	cloud.google.com/go/firestore v1.14.0
 	firebase.google.com/go v3.13.0+incompatible
 	github.com/GoogleCloudPlatform/functions-framework-go v1.8.1
+	github.com/Songmu/flextime v0.1.0
 	github.com/google/go-cmp v0.6.0
 	google.golang.org/api v0.170.0
 )
diff --git a/go.sum b/go.sum
index 25eb624..e69ed0e 100644
--- a/go.sum
+++ b/go.sum
@@ -778,6 +778,8 @@ github.com/GoogleCloudPlatform/functions-framework-go v1.8.1 h1:wMO6lE8uR68ReG+/
 github.com/GoogleCloudPlatform/functions-framework-go v1.8.1/go.mod h1:kKqAKLm08tjDVs37IG/Dl4hC1/go4E85Udn1LeSdAEI=
 github.com/JohnCGriffin/overflow v0.0.0-20211019200055-46fa312c352c/go.mod h1:X0CRv0ky0k6m906ixxpzmDRLvX58TFUKS2eePweuyxk=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
+github.com/Songmu/flextime v0.1.0 h1:sss5IALl84LbvU/cS5D1cKNd5ffT94N2BZwC+esgAJI=
+github.com/Songmu/flextime v0.1.0/go.mod h1:ofUSZ/qj7f1BfQQ6rEH4ovewJ0SZmLOjBF1xa8iE87Q=
 github.com/ajstarks/deck v0.0.0-20200831202436-30c9fc6549a9/go.mod h1:JynElWSGnm/4RlzPXRlREEwqTHAN3T56Bv2ITsFT3gY=
 github.com/ajstarks/deck/generate v0.0.0-20210309230005-c3f852c02e19/go.mod h1:T13YZdzov6OU0A1+RfKZiZN9ca6VeKdBdyDV+BY97Tk=
 github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af/go.mod h1:K08gAheRH3/J6wwsYMMT4xOr94bZjxIelGM0+d/wbFw=
diff --git a/usecase/skill_interactor_test.go b/usecase/skill_interactor_test.go
index 88884eb..4329116 100644
--- a/usecase/skill_interactor_test.go
+++ b/usecase/skill_interactor_test.go
@@ -4,7 +4,10 @@ import (
 	"fmt"
 	"reflect"
 	"testing"
+	"time"
 
+	"github.com/Songmu/flextime"
+	"github.com/google/go-cmp/cmp"
 	"github.com/meriy100/portfolio-api/entities"
 	"github.com/meriy100/portfolio-api/usecase/ports"
 )
@@ -96,16 +99,8 @@ func TestSkillInteractor_IndexSkills(t *testing.T) {
 	}
 }
 
-func findSkill(name string, skills []*entities.Skill) *entities.Skill {
-	for _, s := range skills {
-		if s.Name == name {
-			return s
-		}
-	}
-
-	return nil
-}
 func TestSkillInteractor_UpdateSkills(t *testing.T) {
+	now := time.Date(2021, 1, 1, 0, 0, 0, 0, time.UTC)
 	type fields struct {
 		outputPort      ports.SkillOutputPort
 		postRepository  ports.PostRepository
@@ -132,6 +127,7 @@ func TestSkillInteractor_UpdateSkills(t *testing.T) {
 					Lv:          2,
 					Description: "testD",
 					Category:    entities.Os,
+					Timestamp:   now,
 				},
 			},
 			false,
@@ -139,6 +135,9 @@ func TestSkillInteractor_UpdateSkills(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			flextime.Fix(now)
+			defer flextime.Restore()
+
 			s := &SkillInteractor{
 				outputPort:      tt.fields.outputPort,
 				postRepository:  tt.fields.postRepository,
@@ -151,22 +150,8 @@ func TestSkillInteractor_UpdateSkills(t *testing.T) {
 			if len(tt.want) != len(tt.fields.skillRepository.insert) {
 				t.Errorf("UdateSkills() saved value = %v, want %v", tt.fields.skillRepository.insert, tt.want)
 			}
-
-			for _, wantSkill := range tt.want {
-				expect := findSkill(wantSkill.Name, tt.fields.skillRepository.insert)
-				if expect == nil {
-					t.Fatalf("UpdateSkills() saved value = %v, want %v", tt.fields.skillRepository.insert, tt.want)
-				}
-
-				if expect.Lv != wantSkill.Lv {
-					t.Errorf("UpdateSkills() %v's Lv = %v, want %v", expect.Name, expect.Lv, wantSkill.Lv)
-				}
-				if expect.Category != wantSkill.Category {
-					t.Errorf("UpdateSkills() %v's Category = %v, want %v", expect.Name, expect.Category, wantSkill.Category)
-				}
-				if expect.Description != wantSkill.Description {
-					t.Errorf("UpdateSkills() %v's Description = %v, want %v", expect.Name, expect.Description, wantSkill.Description)
-				}
+			if diff := cmp.Diff(tt.want, tt.fields.skillRepository.insert); diff != "" {
+				t.Errorf("UpdateSkills() mismatch (-want +got):\n%s", diff)
 			}
 		})
 	}