diff --git a/buffer.go b/buffer.go
index 128f077..08fee7d 100644
--- a/buffer.go
+++ b/buffer.go
@@ -89,11 +89,7 @@ func NewMemoryBuffer(cap int) *MemoryBuffer {
 func (mb *MemoryBuffer) Size() int {
 	mb.mutex.RLock()
 	defer mb.mutex.RUnlock()
-	return bufferSize(mb.lines)
-}
-
-func bufferSize(lines []line.Line) int {
-	return len(lines)
+	return len(mb.lines)
 }
 
 func (mb *MemoryBuffer) Reset() {
diff --git a/source.go b/source.go
index 7655419..3bd7a1a 100644
--- a/source.go
+++ b/source.go
@@ -283,7 +283,7 @@ func (s *Source) LineAt(n int) (line.Line, error) {
 func (s *Source) Size() int {
 	s.mutex.RLock()
 	defer s.mutex.RUnlock()
-	return bufferSize(s.lines)
+	return len(s.lines)
 }
 
 func (s *Source) Append(l line.Line) {