diff --git a/src/exec-tool-button.c b/src/exec-tool-button.c
index b68a788..f814ff5 100644
--- a/src/exec-tool-button.c
+++ b/src/exec-tool-button.c
@@ -104,7 +104,7 @@ program_exists (gchar *program)
 }
 
 static void
-execute_default_command ()
+execute_default_command (void)
 {
 	static gchar *command = NULL;
 
@@ -152,7 +152,7 @@ menu_append_item (GtkMenu *menu, gchar *title, gchar *command, gchar *icon_name)
 }
 
 static inline GtkWidget *
-construct_menu ()
+construct_menu (void)
 {
 	GtkWidget *menu = gtk_menu_new ();
 
diff --git a/src/settings-tool-button.c b/src/settings-tool-button.c
index 44bbe2a..b7f29e5 100644
--- a/src/settings-tool-button.c
+++ b/src/settings-tool-button.c
@@ -154,7 +154,7 @@ menu_append_item (GtkMenu *menu, gchar *title, gchar *setting_name, XtmSettings
 }
 
 static inline GtkWidget *
-construct_menu ()
+construct_menu (void)
 {
 	XtmSettings *settings = xtm_settings_get_default ();
 	GtkWidget *menu = gtk_menu_new ();