diff --git a/gst-libs/gst/interfaces/mixer.c b/gst-libs/gst/interfaces/mixer.c
index 6058b9f..53fa498 100644
--- a/gst-libs/gst/interfaces/mixer.c
+++ b/gst-libs/gst/interfaces/mixer.c
@@ -340,7 +340,7 @@ gst_mixer_record_toggled (GstMixer * mixer,
 
 void
 gst_mixer_volume_changed (GstMixer * mixer,
-    GstMixerTrack * track, const gint * volumes)
+    GstMixerTrack * track, gint * volumes)
 {
   g_return_if_fail (mixer != NULL);
   g_return_if_fail (track != NULL);
@@ -353,7 +353,7 @@ gst_mixer_volume_changed (GstMixer * mixer,
 
 void
 gst_mixer_option_changed (GstMixer * mixer,
-    GstMixerOptions * opts, const gchar * value)
+    GstMixerOptions * opts, gchar * value)
 {
   g_return_if_fail (mixer != NULL);
   g_return_if_fail (opts != NULL);
diff --git a/gst-libs/gst/interfaces/mixer.h b/gst-libs/gst/interfaces/mixer.h
index 28c5f11..459a142 100644
--- a/gst-libs/gst/interfaces/mixer.h
+++ b/gst-libs/gst/interfaces/mixer.h
@@ -74,12 +74,6 @@ struct _GstMixerClass {
   void           (* set_record)    (GstMixer      *mixer,
                                     GstMixerTrack *track,
                                     gboolean       record);
-  void          (* set_option)     (GstMixer      *mixer,
-                                    GstMixerOptions *opts,
-                                    gchar         *value);
-  const gchar * (* get_option)     (GstMixer      *mixer,
-                                    GstMixerOptions *opts);
-
   /* signals */
   void (* mute_toggled)   (GstMixer      *mixer,
                            GstMixerTrack *channel,
@@ -95,6 +89,13 @@ struct _GstMixerClass {
                            GstMixerOptions *opts,
                            const gchar   *option);
 
+  /* FIXME 0.11: move set/get function to virtual functions part */
+  void          (* set_option)     (GstMixer      *mixer,
+                                    GstMixerOptions *opts,
+                                    gchar         *value);
+  const gchar * (* get_option)     (GstMixer      *mixer,
+                                    GstMixerOptions *opts);
+
   /*< private >*/
   gpointer _gst_reserved[GST_PADDING];
 };
@@ -128,12 +129,13 @@ void            gst_mixer_mute_toggled   (GstMixer      *mixer,
 void            gst_mixer_record_toggled (GstMixer      *mixer,
                                           GstMixerTrack *track,
                                           gboolean       record);
+/* FIXME 0.11: volumes and value shall be const */
 void            gst_mixer_volume_changed (GstMixer      *mixer,
                                           GstMixerTrack *track,
-                                          const gint    *volumes);
+                                          gint          *volumes);
 void            gst_mixer_option_changed (GstMixer      *mixer,
                                           GstMixerOptions *opts,
-                                          const gchar   *value);
+                                          gchar         *value);
 
 G_END_DECLS
 
