diff --git a/firmware/target/arm/imx233/timer-imx233.c b/firmware/target/arm/imx233/timer-imx233.c
index 9721de5cd3..2812f1adfc 100644
--- a/firmware/target/arm/imx233/timer-imx233.c
+++ b/firmware/target/arm/imx233/timer-imx233.c
@@ -24,7 +24,7 @@
 
 static long timer_cycles = 0;
 
-static void timer_fn()
+static void timer_fn(void)
 {
     if(pfn_timer)
         pfn_timer();