diff --git a/src/core/envelope_and_lfo_widget.cpp b/src/core/envelope_and_lfo_widget.cpp
index 9928353c4..0b6b030de 100644
--- a/src/core/envelope_and_lfo_widget.cpp
+++ b/src/core/envelope_and_lfo_widget.cpp
@@ -124,7 +124,8 @@ envelopeAndLFOWidget::envelopeAndLFOWidget( float _value_for_zero_amount,
 	m_lfoAmountIsZero( FALSE ),
 	m_lfoShapeData( NULL ),
 	m_userWave( eng() ),
-	m_lfoShape( SIN )
+	m_lfoShape( SIN ),
+	m_busyMutex( TRUE )
 {
 	if( s_envGraph == NULL )
 	{