diff --git a/include/Plugin.h b/include/Plugin.h
index 1c8421e59..783437bcc 100644
--- a/include/Plugin.h
+++ b/include/Plugin.h
@@ -133,11 +133,12 @@ public:
 			{
 			}
 
-			virtual void fillDescriptionWidget( QWidget *, const Key * )
+			virtual void fillDescriptionWidget( QWidget *, const Key * ) const
 			{
 			}
 
-			virtual void listSubPluginKeys( Plugin::Descriptor *, KeyList & )
+			virtual void listSubPluginKeys( const Plugin::Descriptor *,
+															KeyList & ) const
 			{
 			}
 
diff --git a/plugins/ladspa_effect/LadspaSubPluginFeatures.cpp b/plugins/ladspa_effect/LadspaSubPluginFeatures.cpp
index fd43021df..bb6cba447 100644
--- a/plugins/ladspa_effect/LadspaSubPluginFeatures.cpp
+++ b/plugins/ladspa_effect/LadspaSubPluginFeatures.cpp
@@ -25,7 +25,6 @@
  *
  */
 
-
 #include <QtGui/QHBoxLayout>
 #include <QtGui/QLabel>
 
@@ -46,7 +45,7 @@ LadspaSubPluginFeatures::LadspaSubPluginFeatures( Plugin::PluginTypes _type ) :
 
 
 void LadspaSubPluginFeatures::fillDescriptionWidget( QWidget * _parent,
-														const Key * _key  )
+													const Key * _key  ) const
 {
 	const ladspa_key_t & lkey = subPluginKeyToLadspaKey( _key );
 	ladspa2LMMS * lm = engine::getLADSPAManager();
@@ -114,8 +113,8 @@ void LadspaSubPluginFeatures::fillDescriptionWidget( QWidget * _parent,
 
 
 
-void LadspaSubPluginFeatures::listSubPluginKeys( Plugin::Descriptor * _desc,
-																KeyList & _kl )
+void LadspaSubPluginFeatures::listSubPluginKeys(
+						const Plugin::Descriptor * _desc, KeyList & _kl ) const
 {
 	ladspa2LMMS * lm = engine::getLADSPAManager();
 
diff --git a/plugins/ladspa_effect/LadspaSubPluginFeatures.h b/plugins/ladspa_effect/LadspaSubPluginFeatures.h
index d2e0ef594..05729e6cb 100644
--- a/plugins/ladspa_effect/LadspaSubPluginFeatures.h
+++ b/plugins/ladspa_effect/LadspaSubPluginFeatures.h
@@ -25,7 +25,6 @@
  *
  */
 
-
 #ifndef _LADSPA_SUBPLUGIN_FEATURES_H
 #define _LADSPA_SUBPLUGIN_FEATURES_H
 
@@ -38,9 +37,11 @@ class LadspaSubPluginFeatures : public Plugin::Descriptor::SubPluginFeatures
 public:
 	LadspaSubPluginFeatures( Plugin::PluginTypes _type );
 
-	virtual void fillDescriptionWidget( QWidget * _parent, const Key * _key );
+	virtual void fillDescriptionWidget( QWidget * _parent,
+												const Key * _key ) const;
 
-	virtual void listSubPluginKeys( Plugin::Descriptor * _desc, KeyList & _kl );
+	virtual void listSubPluginKeys( const Plugin::Descriptor * _desc,
+												KeyList & _kl ) const;
 
 	static ladspa_key_t subPluginKeyToLadspaKey( const Key * _key );
 
diff --git a/plugins/vst_effect/VstSubPluginFeatures.cpp b/plugins/vst_effect/VstSubPluginFeatures.cpp
index 3b89d7691..9052827cf 100644
--- a/plugins/vst_effect/VstSubPluginFeatures.cpp
+++ b/plugins/vst_effect/VstSubPluginFeatures.cpp
@@ -40,18 +40,17 @@ VstSubPluginFeatures::VstSubPluginFeatures( Plugin::PluginTypes _type ) :
 
 
 void VstSubPluginFeatures::fillDescriptionWidget( QWidget * _parent,
-							const Key * _key  )
+													const Key * _key  ) const
 {
 	new QLabel( QWidget::tr( "Name: " ) + _key->name, _parent );
-	new QLabel( QWidget::tr( "File: " ) + _key->attributes["file"],
-								_parent );
+	new QLabel( QWidget::tr( "File: " ) + _key->attributes["file"], _parent );
 }
 
 
 
 
-void VstSubPluginFeatures::listSubPluginKeys( Plugin::Descriptor * _desc,
-								KeyList & _kl )
+void VstSubPluginFeatures::listSubPluginKeys( const Plugin::Descriptor * _desc,
+														KeyList & _kl ) const
 {
 	QStringList dlls = QDir( configManager::inst()->vstDir() ).
 				entryList( QStringList() << "*.dll",
@@ -64,6 +63,5 @@ void VstSubPluginFeatures::listSubPluginKeys( Plugin::Descriptor * _desc,
 		am["file"] = *it;
 		_kl.push_back( Key( _desc, QFileInfo( *it ).baseName(), am ) );
 	}
-
 }
 
diff --git a/plugins/vst_effect/VstSubPluginFeatures.h b/plugins/vst_effect/VstSubPluginFeatures.h
index 0f1377427..62856122e 100644
--- a/plugins/vst_effect/VstSubPluginFeatures.h
+++ b/plugins/vst_effect/VstSubPluginFeatures.h
@@ -35,9 +35,11 @@ class VstSubPluginFeatures : public Plugin::Descriptor::SubPluginFeatures
 public:
 	VstSubPluginFeatures( Plugin::PluginTypes _type );
 
-	virtual void fillDescriptionWidget( QWidget * _parent, const Key * _key );
+	virtual void fillDescriptionWidget( QWidget * _parent,
+											const Key * _key ) const;
 
-	virtual void listSubPluginKeys( Plugin::Descriptor * _desc, KeyList & _kl );
+	virtual void listSubPluginKeys( const Plugin::Descriptor * _desc,
+											KeyList & _kl ) const;
 
 } ;