diff --git a/lumberjack.go b/lumberjack.go
index 2e5d283..7014444 100644
--- a/lumberjack.go
+++ b/lumberjack.go
@@ -252,19 +252,20 @@ func (l *Logger) openExistingOrNew(writeLen int) error {
 	if err != nil {
 		return fmt.Errorf("error getting log file info: %s", err)
 	}
-	// the first file we find that matches our pattern will be the most
-	// recently modified log file.
-	if info.Size()+int64(writeLen) < l.max() {
-		file, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY, 0644)
-		if err == nil {
-			l.file = file
-			l.size = info.Size()
-			return nil
-		}
+
+	if info.Size()+int64(writeLen) >= l.max() {
+		return l.rotate()
+	}
+
+	file, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY, 0644)
+	if err != nil {
 		// if we fail to open the old log file for some reason, just ignore
 		// it and open a new log file.
+		return l.openNew()
 	}
-	return l.openNew()
+	l.file = file
+	l.size = info.Size()
+	return nil
 }
 
 // genFilename generates the name of the logfile from the current time.
@@ -338,7 +339,6 @@ func (l *Logger) oldLogFiles() ([]logInfo, error) {
 		if f.IsDir() {
 			continue
 		}
-
 		name := l.timeFromName(f.Name(), prefix, ext)
 		if name == "" {
 			continue
@@ -347,6 +347,8 @@ func (l *Logger) oldLogFiles() ([]logInfo, error) {
 		if err == nil {
 			logFiles = append(logFiles, logInfo{t, f})
 		}
+		// error parsing means that the suffix at the end was not generated
+		// by lumberjack, and therefore it's not a backup file.
 	}
 
 	sort.Sort(byFormatTime(logFiles))
diff --git a/lumberjack_test.go b/lumberjack_test.go
index e9984f8..c11dc18 100644
--- a/lumberjack_test.go
+++ b/lumberjack_test.go
@@ -308,6 +308,62 @@ func TestMaxBackups(t *testing.T) {
 	exists(notlogfiledir, t)
 }
 
+func TestCleanupExistingBackups(t *testing.T) {
+	// test that if we start with more backup files than we're supposed to have
+	// in total, that extra ones get cleaned up when we rotate.
+
+	currentTime = fakeTime
+	megabyte = 1
+
+	dir := makeTempDir("TestCleanupExistingBackups", t)
+	defer os.RemoveAll(dir)
+
+	// make 3 backup files
+
+	data := []byte("data")
+	backup := backupFile(dir)
+	err := ioutil.WriteFile(backup, data, 0644)
+	isNil(err, t)
+
+	newFakeTime()
+
+	backup = backupFile(dir)
+	err = ioutil.WriteFile(backup, data, 0644)
+	isNil(err, t)
+
+	newFakeTime()
+
+	backup = backupFile(dir)
+	err = ioutil.WriteFile(backup, data, 0644)
+	isNil(err, t)
+
+	// now create a primary log file with some data
+	filename := logFile(dir)
+	err = ioutil.WriteFile(filename, data, 0644)
+	isNil(err, t)
+
+	l := &Logger{
+		Filename:   filename,
+		MaxSize:    10,
+		MaxBackups: 1,
+	}
+	defer l.Close()
+
+	newFakeTime()
+
+	b2 := []byte("foooooo!")
+	n, err := l.Write(b2)
+	isNil(err, t)
+	equals(len(b2), n, t)
+
+	// we need to wait a little bit since the files get deleted on a different
+	// goroutine.
+	<-time.After(time.Millisecond * 10)
+
+	// now we should only have 2 files left - the primary and one backup
+	fileCount(dir, 2, t)
+}
+
 func TestMaxAge(t *testing.T) {
 	currentTime = fakeTime
 	megabyte = 1