diff --git a/desmume/src/gtk/main.cpp b/desmume/src/gtk/main.cpp
index e55403a6d..5bc2c39d7 100644
--- a/desmume/src/gtk/main.cpp
+++ b/desmume/src/gtk/main.cpp
@@ -116,6 +116,7 @@ static void About();
static void ToggleMenuVisible(GtkToggleAction *action);
static void ToggleStatusbarVisible(GtkToggleAction *action);
static void ToggleToolbarVisible(GtkToggleAction *action);
+static void ToggleFullscreen (GtkToggleAction *action);
static void ToggleAudio (GtkToggleAction *action);
#ifdef FAKE_MIC
static void ToggleMicNoise (GtkToggleAction *action);
@@ -247,6 +248,7 @@ static const char *ui_description =
" "
" "
" "
+" "
" "
" "
"