diff --git a/main.go b/main.go
index a2095d6..0c506d8 100644
--- a/main.go
+++ b/main.go
@@ -12,11 +12,12 @@ func executor(b *prompt.Buffer) string {
 }
 
 func completer(b *prompt.Buffer) []string {
-	return []string{"foo", "bar", "baz"}
+	return []string{"select", "from", "insert", "where"}
 }
 
 func main() {
-	pt := prompt.NewPrompt(executor)
+	pt := prompt.NewPrompt(executor, completer)
 	defer fmt.Println("\nGoodbye!")
+	fmt.Print("Hello! This is a example appication using prompt-toolkit.\n\n")
 	pt.Run()
 }
diff --git a/prompt/prompt.go b/prompt/prompt.go
index 5da08bc..c0e3b7b 100644
--- a/prompt/prompt.go
+++ b/prompt/prompt.go
@@ -8,14 +8,16 @@ import (
 )
 
 type Executor func(*Buffer) string
+type Completer func(*Buffer) []string
 
 type Prompt struct {
-	in       *VT100Parser
-	out      *VT100Writer
-	buf      *Buffer
-	renderer *Render
-	title    string
-	executor Executor
+	in        *VT100Parser
+	out       *VT100Writer
+	buf       *Buffer
+	renderer  *Render
+	title     string
+	executor  Executor
+	completer Completer
 }
 
 func (p *Prompt) Run() {
@@ -54,7 +56,8 @@ func (p *Prompt) Run() {
 
 			// Display completions
 			if w := p.buf.Document().GetWordBeforeCursor(); w != "" {
-				p.renderer.RenderCompletion([]string{})
+				completions := p.completer(p.buf)
+				p.renderer.RenderCompletion(completions)
 			}
 
 			completions := []string{"select", "insert", "update", "where"}
@@ -133,7 +136,7 @@ func handleSignals(in *VT100Parser, exitCh chan bool, winSizeCh chan *WinSize) {
 	}
 }
 
-func NewPrompt(executor Executor) *Prompt {
+func NewPrompt(executor Executor, completer Completer) *Prompt {
 	out := NewVT100Writer()
 	return &Prompt{
 		in: NewVT100Parser(),
@@ -145,5 +148,6 @@ func NewPrompt(executor Executor) *Prompt {
 		title: "Hello! this is prompt toolkit",
 		buf: NewBuffer(),
 		executor: executor,
+		completer: completer,
 	}
 }
diff --git a/prompt/render.go b/prompt/render.go
index a04bf25..6a11921 100644
--- a/prompt/render.go
+++ b/prompt/render.go
@@ -24,42 +24,44 @@ func (r *Render) UpdateWinSize(ws *WinSize) {
 }
 
 func (r *Render) RenderCompletion(words []string) {
-	r.PrepareArea(4)
-	r.out.SetColor("white", "teal")
+	formatted, width := formatCompletions(words)
+	l := len(formatted)
+	r.PrepareArea(l)
 
-	r.out.CursorDown(1)
-	r.out.Write([]byte(" select "))
-	r.out.SetColor("white", "darkGray")
-	r.out.Write([]byte(" "))
 	r.out.SetColor("white", "teal")
-	r.out.CursorBackward(len("select") + 3)
+	for i := 0; i < l; i++ {
+		r.out.CursorDown(1)
+		r.out.WriteStr(" " + formatted[i] + " ")
+		r.out.SetColor("white", "darkGray")
+		r.out.Write([]byte(" "))
+		r.out.SetColor("white", "teal")
+		r.out.CursorBackward(width + 3)
+	}
 
-	r.out.CursorDown(1)
-	r.out.Write([]byte(" insert "))
-	r.out.SetColor("white", "darkGray")
-	r.out.Write([]byte(" "))
-	r.out.SetColor("white", "teal")
-	r.out.CursorBackward(len("insert") + 3)
-
-	r.out.CursorDown(1)
-	r.out.Write([]byte(" update "))
-	r.out.SetColor("white", "darkGray")
-	r.out.Write([]byte(" "))
-	r.out.SetColor("white", "teal")
-	r.out.CursorBackward(len("update") + 3)
-
-	r.out.CursorDown(1)
-	r.out.Write([]byte(" where  "))
-	r.out.SetColor("white", "darkGray")
-	r.out.Write([]byte(" "))
-	r.out.SetColor("white", "teal")
-	r.out.CursorBackward(len("where ") + 3)
-
-	r.out.CursorUp(4)
+	r.out.CursorUp(l)
 	r.out.SetColor("default", "default")
 	return
 }
 
+func formatCompletions(words []string) ([]string, int) {
+	num := len(words)
+	width := 0
+
+	for i := 0; i < num; i++ {
+		if width < len([]rune(words[i])) {
+			width = len([]rune(words[i]))
+		}
+	}
+
+	for i := 0; i < num; i++ {
+		spaces := width - len([]rune(words[i]))
+		for j := 0; j < spaces; j++ {
+			words[i] += " "
+		}
+	}
+	return words, width
+}
+
 func (r *Render) Render(buffer *Buffer, completions []string) {
 	r.out.Flush()
 }
diff --git a/prompt/render_test.go b/prompt/render_test.go
new file mode 100644
index 0000000..c581c70
--- /dev/null
+++ b/prompt/render_test.go
@@ -0,0 +1,29 @@
+package prompt
+
+import (
+	"testing"
+	"reflect"
+)
+
+func TestFormatCompletion(t *testing.T) {
+	in := []string {
+		"select",
+		"from",
+		"insert",
+		"where",
+	}
+	ex := []string{
+		"select",
+		"from  ",
+		"insert",
+		"where ",
+	}
+
+	ac, width := formatCompletions(in)
+	if !reflect.DeepEqual(ac, ex) {
+		t.Errorf("Should be %#v, but got %#v", ex, ac)
+	}
+	if width != 6 {
+		t.Errorf("Should be %#v, but got %#v", 4, width)
+	}
+}