diff --git a/ui/drivers/null/ui_null_application.c b/ui/drivers/null/ui_null_application.c
index 47545160fe..6704a22cec 100644
--- a/ui/drivers/null/ui_null_application.c
+++ b/ui/drivers/null/ui_null_application.c
@@ -21,7 +21,7 @@
 
 #include "../../ui_companion_driver.h"
 
-void ui_application_null_process_events(void *data)
+static void ui_application_null_process_events(void *data)
 {
 }
 
diff --git a/ui/drivers/null/ui_null_window.c b/ui/drivers/null/ui_null_window.c
index 9a26741397..ec0b889d8e 100644
--- a/ui/drivers/null/ui_null_window.c
+++ b/ui/drivers/null/ui_null_window.c
@@ -21,11 +21,11 @@
 
 #include "../../ui_companion_driver.h"
 
-void ui_window_null_destroy(void *data)
+static void ui_window_null_destroy(void *data)
 {
 }
 
-void ui_window_null_set_focused(void *data)
+static void ui_window_null_set_focused(void *data)
 {
 }