diff --git a/objective-lisp.lisp b/objective-lisp.lisp
index d576896..e6156ee 100644
--- a/objective-lisp.lisp
+++ b/objective-lisp.lisp
@@ -14,14 +14,16 @@
   (let ((expr root))
     (loop for entry on forms
           for form = (car entry)
-          do (setf expr
-                   (cond ((consp form) `(,(car form) ,expr ,@(cdr form)))
-                         ((eq form :slot) (prog1
-                                              `(slot-value ,expr ',(cadr entry))
-                                            (rplacd entry (cddr entry))))
-                         ((symbolp form) `(,form ,expr))
-                         (t (error "Unexpected form ~S" form))
-                   )))
+          and prev-form = nil then form
+          unless (eq prev-form :slot)
+            do (setf expr
+                     (cond ((consp form) `(,(car form) ,expr ,@(cdr form)))
+                           ((eq form :slot) (prog1 `(slot-value ,expr ',(cadr entry))
+                                              (unless (cadr entry)
+                                                (error "Missing slot name"))))
+                           ((symbolp form) `(,form ,expr))
+                           (t (error "Unexpected form ~S" form)))))
+    ;(format t "~S => ~S~%" `(O! ,root ,@forms) expr)
     expr))
 
 (defun read-construct (stream char arg)