diff --git a/src/gui/widgets/widget_helpers.cpp b/src/gui/widgets/widget_helpers.cpp
index c1ad72bb864f..f64b2d87637d 100644
--- a/src/gui/widgets/widget_helpers.cpp
+++ b/src/gui/widgets/widget_helpers.cpp
@@ -12,6 +12,8 @@
    See the COPYING file for more details.
 */
 
+#include "gui/widgets/widget_helpers.hpp"
+
 #include "gui/auxiliary/find_widget.hpp"
 #include "gui/widgets/grid.hpp"
 #include "gui/widgets/widget.hpp"
diff --git a/src/sound.hpp b/src/sound.hpp
index c54bb8da0a73..20eb6ff6dc68 100644
--- a/src/sound.hpp
+++ b/src/sound.hpp
@@ -106,6 +106,7 @@ void set_UI_volume(int vol);
 
 unsigned int get_current_track();
 std::shared_ptr<sound::music_track> get_previous_music_track();
+void set_previous_track(std::shared_ptr<music_track>);
 unsigned int get_num_tracks();
 void remove_track(unsigned int i);
 void play_track(unsigned int i);