diff --git a/objective-lisp.lisp b/objective-lisp.lisp
index b6d285d..19d798e 100644
--- a/objective-lisp.lisp
+++ b/objective-lisp.lisp
@@ -16,10 +16,10 @@
           for form = (car entry)
           do (setf expr
                    (cond ((consp form) `(,(car form) ,expr ,@(cdr form)))
-                         ((eq form :slot) (prog1
+                         ((eq form :slot) (prog2
+                                              (unless (cadr entry)
+                                                (error "Unexpected end of list (expected slot name)"))
                                               `(slot-value ,expr ',(cadr entry))
-                                            (unless (cdr entry)
-                                              (error "Unexpected end of list (expected slot name)"))
                                             (rplacd entry (cddr entry))))
                          ((symbolp form) `(,form ,expr))
                          (t (error "Unexpected form ~S" form))