diff --git a/liner/common.go b/liner/common.go
index c8fd015..bc8ecda 100644
--- a/liner/common.go
+++ b/liner/common.go
@@ -32,6 +32,17 @@ type commonState struct {
 	needRefresh       bool
 }
 
+type HistoryProvider interface {
+	ReadHistory(r io.Reader) (num int, err error)
+	WriteHistory(w io.Writer) (num int, err error)
+	AppendHistory(item string)
+	ClearHistory()
+	GetHistoryByPrefix(prefix string) (ph []string)
+	GetHistoryByPattern(pattern string) (ph []string, pos []int)
+	RLock()
+	RUnlock()
+}
+
 // TabStyle is used to select how tab completions are displayed.
 type TabStyle int
 
diff --git a/liner/historyprovider.go b/liner/historyprovider.go
deleted file mode 100644
index dd8659b..0000000
--- a/liner/historyprovider.go
+++ /dev/null
@@ -1,136 +0,0 @@
-package liner
-
-import (
-	"bufio"
-	"fmt"
-	"io"
-	"strings"
-	"sync"
-	"unicode/utf8"
-)
-
-type HistoryProvider interface {
-	ReadHistory(r io.Reader) (num int, err error)
-	WriteHistory(w io.Writer) (num int, err error)
-	AppendHistory(item string)
-	ClearHistory()
-	GetHistoryByPrefix(prefix string) (ph []string)
-	GetHistoryByPattern(pattern string) (ph []string, pos []int)
-	RLock()
-	RUnlock()
-}
-
-type defaultHistoryProvider struct {
-	history      []string
-	historyMutex sync.RWMutex
-}
-
-// RUnlock unlocks history for reading
-func (s *defaultHistoryProvider) RUnlock() {
-	s.historyMutex.RUnlock()
-}
-
-// RUnlock locks history for reading
-func (s *defaultHistoryProvider) RLock() {
-	s.historyMutex.RLock()
-}
-
-// ReadHistory reads scrollback history from r. Returns the number of lines
-// read, and any read error (except io.EOF).
-func (s *defaultHistoryProvider) ReadHistory(r io.Reader) (num int, err error) {
-	s.historyMutex.Lock()
-	defer s.historyMutex.Unlock()
-
-	in := bufio.NewReader(r)
-	num = 0
-	for {
-		line, part, err := in.ReadLine()
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			return num, err
-		}
-		if part {
-			return num, fmt.Errorf("line %d is too long", num+1)
-		}
-		if !utf8.Valid(line) {
-			return num, fmt.Errorf("invalid string at line %d", num+1)
-		}
-		num++
-		s.history = append(s.history, string(line))
-		if len(s.history) > HistoryLimit {
-			s.history = s.history[1:]
-		}
-	}
-	return num, nil
-}
-
-// WriteHistory writes scrollback history to w. Returns the number of lines
-// successfully written, and any write error.
-//
-// Unlike the rest of liner's API, WriteHistory is safe to call
-// from another goroutine while Prompt is in progress.
-// This exception is to facilitate the saving of the history buffer
-// during an unexpected exit (for example, due to Ctrl-C being invoked)
-func (s *defaultHistoryProvider) WriteHistory(w io.Writer) (num int, err error) {
-	s.historyMutex.RLock()
-	defer s.historyMutex.RUnlock()
-
-	for _, item := range s.history {
-		_, err := fmt.Fprintln(w, item)
-		if err != nil {
-			return num, err
-		}
-		num++
-	}
-	return num, nil
-}
-
-// AppendHistory appends an entry to the scrollback history. AppendHistory
-// should be called iff Prompt returns a valid command.
-func (s *defaultHistoryProvider) AppendHistory(item string) {
-	s.historyMutex.Lock()
-	defer s.historyMutex.Unlock()
-
-	if len(s.history) > 0 {
-		if item == s.history[len(s.history)-1] {
-			return
-		}
-	}
-	s.history = append(s.history, item)
-	if len(s.history) > HistoryLimit {
-		s.history = s.history[1:]
-	}
-}
-
-// ClearHistory clears the scrollback history.
-func (s *defaultHistoryProvider) ClearHistory() {
-	s.historyMutex.Lock()
-	defer s.historyMutex.Unlock()
-	s.history = nil
-}
-
-// Returns the history lines starting with prefix
-func (s *defaultHistoryProvider) getHistoryByPrefix(prefix string) (ph []string) {
-	for _, h := range s.history {
-		if strings.HasPrefix(h, prefix) {
-			ph = append(ph, h)
-		}
-	}
-	return
-}
-
-// Returns the history lines matching the intelligent search
-func (s *defaultHistoryProvider) getHistoryByPattern(pattern string) (ph []string, pos []int) {
-	if pattern == "" {
-		return
-	}
-	for _, h := range s.history {
-		if i := strings.Index(h, pattern); i >= 0 {
-			ph = append(ph, h)
-			pos = append(pos, i)
-		}
-	}
-	return
-}