diff --git a/forge/forge.lisp b/forge/forge.lisp
index 8eb0ee4..cdfe523 100644
--- a/forge/forge.lisp
+++ b/forge/forge.lisp
@@ -13,7 +13,9 @@
 (defclass forge-env ()
   ((data-stack :initform nil
 			   :reader data-stack
-			   :accessor data-stack!)))
+			   :accessor data-stack!)
+   (vocabulary :initform (list *builtins*)
+			   :accessor vocabulary)))
 
 (defun forge-env ()
   (make-instance 'forge-env))
@@ -21,12 +23,18 @@
 (defun exec (fe code)
   (dolist (x code)
 	(if (symbolp x)
-      (funcall (gethash (string-downcase (symbol-name x)) *builtins*) fe)
+      (funcall (find-word (vocabulary fe) x) fe)
 	  (pushd fe x))))
 
 (defun register (voc key fn)
   (setf (gethash (string-downcase (symbol-name key)) voc) fn))
 
+(defun find-word (vocab key)
+  (let ((k (string-downcase (symbol-name key))) (result nil))
+    (dolist (voc vocab)
+	  (let ((v (gethash k voc)))
+		(if v (return v))))))
+
 ; built-in primitives
 
 (defun reg-b (key fn) (register *builtins* key fn))