diff --git a/inc/hf/api.h b/inc/hf/api.h
index a0151c0..21bed0c 100644
--- a/inc/hf/api.h
+++ b/inc/hf/api.h
@@ -23,7 +23,7 @@
 #include "vmapi/hf/call.h"
 
 void api_init(struct mpool *ppool);
-int64_t api_vm_get_id(const struct vcpu *current);
+spci_vm_id_t api_vm_get_id(const struct vcpu *current);
 int64_t api_vm_get_count(void);
 int64_t api_vcpu_get_count(spci_vm_id_t vm_id, const struct vcpu *current);
 void api_regs_state_saved(struct vcpu *vcpu);
diff --git a/src/api.c b/src/api.c
index 59a346d..698e788 100644
--- a/src/api.c
+++ b/src/api.c
@@ -208,7 +208,7 @@
 /**
  * Returns the ID of the VM.
  */
-int64_t api_vm_get_id(const struct vcpu *current)
+spci_vm_id_t api_vm_get_id(const struct vcpu *current)
 {
 	return current->vm->id;
 }