diff --git a/README.md b/README.md
index 919adba..6c4853e 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ go get github.com/rhnvrm/simples3
 ## Example
 
 ```go
-testTxt, _ := os.Open("test.txt")
+testTxt, _ := os.Open("testdata/test.txt")
 defer testTxt.Close()
 
 // Create an instance of the package
@@ -24,6 +24,9 @@ s3 := simples3.New(Region, AWSAccessKey, AWSSecretKey)
 // obtain credentials from IAM attached to the instance.
 s3 := simples3.NewUsingIAM(Region)
 
+// You can also set a custom endpoint to a compatible s3 instance. 
+s3.SetEndpoint(CustomEndpoint)
+
 // Note: Consider adding a testTxt.Seek(0, 0)
 // in case you have read 
 // the body, as the pointer is shared by the library.
diff --git a/go.mod b/go.mod
index dda828e..99c1501 100644
--- a/go.mod
+++ b/go.mod
@@ -1 +1,3 @@
 module github.com/rhnvrm/simples3
+
+go 1.13
diff --git a/policy.go b/policy.go
index 33d0357..e8562cb 100644
--- a/policy.go
+++ b/policy.go
@@ -55,8 +55,8 @@ const (
 	defaultExpirationHour  = 1 * time.Hour
 )
 
-// NowTime mockable time.Now()
-var NowTime = func() time.Time {
+// nowTime mockable time.Now()
+var nowTime = func() time.Time {
 	return time.Now().UTC()
 }
 
@@ -66,7 +66,7 @@ var newLine = []byte{'\n'}
 // policy and signing keys with the signature returns the upload policy.
 // https://docs.aws.amazon.com/ja_jp/AmazonS3/latest/API/sigv4-authentication-HTTPPOST.html
 func (s3 *S3) CreateUploadPolicies(uploadConfig UploadConfig) (UploadPolicies, error) {
-	nowTime := NowTime()
+	nowTime := nowTime()
 	credential := string(s3.buildCredential(nowTime))
 	data, err := buildUploadSign(nowTime, credential, uploadConfig)
 	if err != nil {
diff --git a/presigned.go b/presigned.go
index 3ead23e..ca5f3f2 100644
--- a/presigned.go
+++ b/presigned.go
@@ -33,7 +33,7 @@ type PresignedInput struct {
 // (https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html)
 func (s3 *S3) GeneratePresignedURL(in PresignedInput) string {
 	var (
-		nowTime = NowTime()
+		nowTime = nowTime()
 
 		protocol = defaultProtocol
 		endpoint = defaultPresignedHost
diff --git a/presigned_test.go b/presigned_test.go
index f4607f1..c03ff6b 100644
--- a/presigned_test.go
+++ b/presigned_test.go
@@ -42,7 +42,7 @@ func TestS3_GeneratePresignedURL_Personal(t *testing.T) {
 			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test1.txt",
 			Method:        "GET",
-			Timestamp:     NowTime(),
+			Timestamp:     nowTime(),
 			ExpirySeconds: 3600,
 		}); got == dontwant {
 			t.Errorf("S3.GeneratePresignedURL() = %v, dontwant %v", got, dontwant)
@@ -63,7 +63,7 @@ func TestS3_GeneratePresignedURL_ExtraHeader(t *testing.T) {
 			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test2.txt",
 			Method:        "GET",
-			Timestamp:     NowTime(),
+			Timestamp:     nowTime(),
 			ExpirySeconds: 3600,
 			ExtraHeaders: map[string]string{
 				"x-amz-meta-test": "test",
@@ -87,7 +87,7 @@ func TestS3_GeneratePresignedURL_PUT(t *testing.T) {
 			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test2.txt",
 			Method:        "PUT",
-			Timestamp:     NowTime(),
+			Timestamp:     nowTime(),
 			ExpirySeconds: 3600,
 		}); got == dontwant {
 			t.Errorf("S3.GeneratePresignedURL() = %v, dontwant %v", got, dontwant)
@@ -111,7 +111,7 @@ func BenchmarkS3_GeneratePresigned(b *testing.B) {
 			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test.txt",
 			Method:        "GET",
-			Timestamp:     NowTime(),
+			Timestamp:     nowTime(),
 			ExpirySeconds: 3600,
 		})
 	}
diff --git a/simples3.go b/simples3.go
index e30641f..2774f0d 100644
--- a/simples3.go
+++ b/simples3.go
@@ -158,7 +158,8 @@ func (s3 *S3) getURL(bucket string, args ...string) (uri string) {
 	return
 }
 
-// SetEndpoint ...
+// SetEndpoint can be used to the set a custom endpoint for
+// using an alternate instance compatible with the s3 API.
 func (s3 *S3) SetEndpoint(uri string) *S3 {
 	if len(uri) > 0 {
 		s3.Endpoint = uri
diff --git a/simples3_test.go b/simples3_test.go
index 843eab8..fc6c160 100644
--- a/simples3_test.go
+++ b/simples3_test.go
@@ -16,7 +16,7 @@ type tConfig struct {
 }
 
 func TestS3_FileUpload(t *testing.T) {
-	testTxt, err := os.Open("test.txt")
+	testTxt, err := os.Open("testdata/test.txt")
 	if err != nil {
 		return
 	}
@@ -75,7 +75,8 @@ func TestS3_FileUpload(t *testing.T) {
 			wantErr: false,
 		},
 	}
-	for _, tt := range tests {
+	for _, testcase := range tests {
+		tt := testcase
 		t.Run(tt.name, func(t *testing.T) {
 			s3 := New(tt.fields.Region, tt.fields.AccessKey, tt.fields.SecretKey)
 			s3.SetEndpoint(tt.fields.Endpoint)
@@ -118,7 +119,8 @@ func TestS3_FileDelete(t *testing.T) {
 			wantErr: false,
 		},
 	}
-	for _, tt := range tests {
+	for _, testcase := range tests {
+		tt := testcase
 		t.Run(tt.name, func(t *testing.T) {
 			s3 := New(tt.fields.Region, tt.fields.AccessKey, tt.fields.SecretKey)
 			s3.SetEndpoint(tt.fields.Endpoint)
diff --git a/test.txt b/testdata/test.txt
similarity index 100%
rename from test.txt
rename to testdata/test.txt