diff --git a/sys/arm/mv/armada/wdt.c b/sys/arm/mv/armada/wdt.c
index 7e0887e3513..be0b607cd2b 100644
--- a/sys/arm/mv/armada/wdt.c
+++ b/sys/arm/mv/armada/wdt.c
@@ -69,6 +69,7 @@ struct mv_wdt_config {
 static void mv_wdt_enable_armv5(void);
 static void mv_wdt_enable_armada_38x(void);
 static void mv_wdt_enable_armada_xp(void);
+static inline void mv_wdt_enable_armada_38x_xp_helper(void);
 
 static void mv_wdt_disable_armv5(void);
 static void mv_wdt_disable_armada_38x(void);
@@ -232,7 +233,7 @@ mv_wdt_enable_armv5(void)
 }
 
 static inline void
-mv_wdt_enable_armada_38x_xp_helper()
+mv_wdt_enable_armada_38x_xp_helper(void)
 {
 	uint32_t val, irq_cause;