diff --git a/fibs.s b/fibs.s
index 3d35544..84ebc6b 100644
--- a/fibs.s
+++ b/fibs.s
@@ -30,8 +30,8 @@
 .thunkcode fibs0
 	thunkto %r12, $INT_code, $1
 	thunkto %r11, $INT_code, $0
-	thunkto %rbp, $fibs, $2, %r11, %r12
-	enter_rbp
+	thunk $fibs, $2, %r11, %r12
+	enter %rsp
 
 .thunkcode main
 	thunkto %r12, $fibs0, $0