diff --git a/markdown.go b/markdown.go
index 337e289..bbc3db5 100644
--- a/markdown.go
+++ b/markdown.go
@@ -72,6 +72,11 @@ type Formatter interface {
 func (p *Parser) Markdown(src io.Reader, f Formatter) {
 	s := p.preformat(src)
 
+	// this should not be necessary;
+	// investigation is needed to understand
+	// why the buffer sometimes is not empty
+	p.yy.ResetBuffer("")
+
 	p.parseRule(ruleReferences, s)
 	if p.yy.extension.Notes {
 		p.parseRule(ruleNotes, s)