diff --git a/inc/vmapi/hf/call.h b/inc/vmapi/hf/call.h
index a8904b6..d059196 100644
--- a/inc/vmapi/hf/call.h
+++ b/inc/vmapi/hf/call.h
@@ -50,7 +50,7 @@
 /**
  * Returns the VM's own ID.
  */
-static inline uint32_t hf_vm_get_id()
+static inline uint32_t hf_vm_get_id(void)
 {
 	return hf_call(HF_VM_GET_ID, 0, 0, 0);
 }