diff --git a/include/btstack/hal_cpu.h b/include/btstack/hal_cpu.h
index db87f9cb4..92dfb5d68 100644
--- a/include/btstack/hal_cpu.h
+++ b/include/btstack/hal_cpu.h
@@ -36,8 +36,8 @@
  *  and then unblocked while entering low power mode atomically
  */
  
-void hal_cpu_disable_irqs();
-void hal_cpu_enable_irqs();
-void hal_cpu_enable_irqs_and_sleep();
+void hal_cpu_disable_irqs(void);
+void hal_cpu_enable_irqs(void);
+void hal_cpu_enable_irqs_and_sleep(void);
 
  
\ No newline at end of file