diff --git a/src/json-rpc2.lisp b/src/json-rpc2.lisp
index 8bf3d44..dee71cb 100644
--- a/src/json-rpc2.lisp
+++ b/src/json-rpc2.lisp
@@ -124,7 +124,7 @@
 
 (defmacro make-json-rpc-error (code message)
   `(progn
-     (assert (< -32000 code -32099))
+     (assert (< -32000 ,code -32099))
      (error 'json-rpc-error  :text ,message :code ,code)))
 
 (defparameter *function-db* '())