diff --git a/completion.go b/completion.go
index 3afd730..2aff2ef 100644
--- a/completion.go
+++ b/completion.go
@@ -22,6 +22,7 @@ func (c *CompletionManager) GetSelectedSuggestion() (s Suggest, ok bool) {
 		return Suggest{}, false
 	} else if c.selected < -1 {
 		log.Printf("[ERROR] shoud be reached here, selected=%d", c.selected)
+		c.selected = -1
 		return Suggest{}, false
 	}
 	return c.tmp[c.selected], true
diff --git a/render.go b/render.go
index f650a06..99e3ca2 100644
--- a/render.go
+++ b/render.go
@@ -1,9 +1,5 @@
 package prompt
 
-import (
-	"log"
-)
-
 const (
 	leftPrefix       = " "
 	leftSuffix       = " "
@@ -98,7 +94,6 @@ func (r *Render) renderCompletion(buf *Buffer, completions *CompletionManager) {
 		suggestions,
 		int(r.col)-len(r.prefix),
 	)
-	log.Printf("[INFO] formatted: %#v\n", formatted)
 	l := len(formatted)
 	r.prepareArea(l)
 
diff --git a/vt100_output.go b/vt100_output.go
index 4d7eba5..fd7349d 100644
--- a/vt100_output.go
+++ b/vt100_output.go
@@ -12,6 +12,8 @@ type VT100Writer struct {
 
 func (w *VT100Writer) WriteRaw(data []byte) {
 	w.buffer = append(w.buffer, data...)
+	// Flush because sometimes the render is broken when a large amount data in buffer.
+	w.Flush()
 	return
 }