diff --git a/src/vm.c b/src/vm.c
index 9e8a26c3..995bc545 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -9,6 +9,7 @@
 #include "picrin/proc.h"
 #include "picrin/irep.h"
 #include "picrin/blob.h"
+#include "picrin/var.h"
 
 #define GET_OPERAND(pic,n) ((pic)->ci->fp[(n)])
 
@@ -309,6 +310,15 @@ pic_defun(pic_state *pic, const char *name, pic_func_t cfunc)
   pic_define(pic, pic->lib, name, pic_obj_value(proc));
 }
 
+void
+pic_defvar(pic_state *pic, const char *name, pic_value init)
+{
+  struct pic_var *var;
+
+  var = pic_var_new(pic, init, NULL);
+  pic_define(pic, pic->lib, name, pic_obj_value(pic_wrap_var(pic, var)));
+}
+
 pic_value
 pic_apply_argv(pic_state *pic, struct pic_proc *proc, size_t argc, ...)
 {