diff --git a/interfaces.go b/interfaces.go
index 6582498..a220396 100644
--- a/interfaces.go
+++ b/interfaces.go
@@ -1,5 +1,9 @@
 package strumt
 
+import (
+	"io"
+)
+
 // Prompter defines a generic common prompt.
 //
 // ID returns a string id to identify prompter and to let other prompter call it.
@@ -45,18 +49,18 @@ type MultilinePrompter interface {
 // PromptRenderer can be implemented to customize
 // the way prompt is rendered, PromptString result is given as parameter
 type PromptRenderer interface {
-	PrintPrompt(string)
+	PrintPrompt(io.Writer, string)
 }
 
 // ErrorRenderer can be implemented to customize
 // the way an error returned by Parse is rendered
 type ErrorRenderer interface {
-	PrintError(err error)
+	PrintError(io.Writer, error)
 }
 
 // SeparatorRenderer can be implemented to customize
 // the way a prompt is separated from another, default
 // is to add a new line
 type SeparatorRenderer interface {
-	PrintSeparator()
+	PrintSeparator(io.Writer)
 }
diff --git a/prompt_example_customize_output_test.go b/prompt_example_customize_output_test.go
index 9c15ddf..e8c778c 100644
--- a/prompt_example_customize_output_test.go
+++ b/prompt_example_customize_output_test.go
@@ -61,10 +61,10 @@ func (a *AreYouOkPrompt) NextOnError(err error) string {
 	return "okprompt"
 }
 
-func (a *AreYouOkPrompt) PrintPrompt(prompt string) {
-	fmt.Printf("==> %s\n", prompt)
+func (a *AreYouOkPrompt) PrintPrompt(w io.Writer, prompt string) {
+	fmt.Fprintf(w, "==> %s\n", prompt)
 }
 
-func (a *AreYouOkPrompt) PrintError(err error) {
-	fmt.Printf("An error occurred : %s\n", err)
+func (a *AreYouOkPrompt) PrintError(w io.Writer, err error) {
+	fmt.Fprintf(w, "An error occurred : %s", err)
 }
diff --git a/prompts.go b/prompts.go
index 99e8ee3..c41da05 100644
--- a/prompts.go
+++ b/prompts.go
@@ -205,7 +205,7 @@ func parseLine(reader *bufio.Reader, prompt LinePrompter) (string, error) {
 func renderPrompt(writer io.Writer, prompt Prompter) {
 	switch pr := prompt.(type) {
 	case PromptRenderer:
-		pr.PrintPrompt(prompt.PromptString())
+		pr.PrintPrompt(writer, prompt.PromptString())
 	default:
 		fmt.Fprintf(writer, "%s\n", prompt.PromptString())
 	}
@@ -214,7 +214,7 @@ func renderPrompt(writer io.Writer, prompt Prompter) {
 func renderError(writer io.Writer, prompt Prompter, err error) {
 	switch pr := prompt.(type) {
 	case ErrorRenderer:
-		pr.PrintError(err)
+		pr.PrintError(writer, err)
 	default:
 		fmt.Fprintf(writer, "%s\n", err.Error())
 	}
@@ -223,7 +223,7 @@ func renderError(writer io.Writer, prompt Prompter, err error) {
 func renderSeparator(writer io.Writer, prompt Prompter) {
 	switch pr := prompt.(type) {
 	case SeparatorRenderer:
-		pr.PrintSeparator()
+		pr.PrintSeparator(writer)
 	default:
 		fmt.Fprintf(writer, "\n")
 	}
diff --git a/prompts_test.go b/prompts_test.go
index 5529a9d..d9c9743 100644
--- a/prompts_test.go
+++ b/prompts_test.go
@@ -231,7 +231,6 @@ type StringWithCustomRendererPrompt struct {
 	currentID         string
 	nextPrompt        string
 	nextPromptOnError string
-	writer            io.Writer
 }
 
 func (s *StringWithCustomRendererPrompt) ID() string {
@@ -260,26 +259,26 @@ func (s *StringWithCustomRendererPrompt) NextOnError(err error) string {
 	return s.nextPromptOnError
 }
 
-func (s *StringWithCustomRendererPrompt) PrintPrompt(prompt string) {
-	fmt.Fprintf(s.writer, "==> %s : \n", prompt)
+func (s *StringWithCustomRendererPrompt) PrintPrompt(w io.Writer, prompt string) {
+	fmt.Fprintf(w, "==> %s : \n", prompt)
 }
 
-func (s *StringWithCustomRendererPrompt) PrintError(err error) {
-	fmt.Fprintf(s.writer, "==> Something went wrong : %s\n", err.Error())
+func (s *StringWithCustomRendererPrompt) PrintError(w io.Writer, err error) {
+	fmt.Fprintf(w, "==> Something went wrong : %s\n", err.Error())
 }
 
-func (s *StringWithCustomRendererPrompt) PrintSeparator() {
-	fmt.Fprintf(s.writer, "\n+++\n")
+func (s *StringWithCustomRendererPrompt) PrintSeparator(w io.Writer) {
+	fmt.Fprintf(w, "\n+++\n")
 }
 
 func TestPromptRunWithCustomRenderer(t *testing.T) {
 	var actualStdout bytes.Buffer
 
-	p := NewPromptsFromReaderAndWriter(bytes.NewBufferString("\ntest\n"), ioutil.Discard)
+	p := NewPromptsFromReaderAndWriter(bytes.NewBufferString("\ntest\n"), &actualStdout)
 
 	var value string
 
-	p.AddLinePrompter(&StringWithCustomRendererPrompt{&value, "Give a value", "test", "", "test", &actualStdout})
+	p.AddLinePrompter(&StringWithCustomRendererPrompt{&value, "Give a value", "test", "", "test"})
 
 	p.SetFirst("test")
 	p.Run()