diff --git a/lib_ppc/interrupts.c b/lib_ppc/interrupts.c
index b803952..c5951e9 100644
--- a/lib_ppc/interrupts.c
+++ b/lib_ppc/interrupts.c
@@ -32,7 +32,12 @@
 #endif
 
 #ifdef CONFIG_SHOW_ACTIVITY
-	extern void board_show_activity (ulong);
+void board_show_activity (ulong) __attribute__((weak, alias("__board_show_activity")));
+
+void __board_show_activity (ulong dummy)
+{
+	return;
+}
 #endif /* CONFIG_SHOW_ACTIVITY */
 
 #ifndef CFG_WATCHDOG_FREQ