diff --git a/serialize-lib.lisp b/serialize-lib.lisp
index c991c11..2e0863c 100644
--- a/serialize-lib.lisp
+++ b/serialize-lib.lisp
@@ -15,13 +15,14 @@
        (cl-ppcre:regex-replace-all "&[:nr&]" ,seq #',replacef :simple-calls t))))
 
 (defmacro string-to-value (seq table-allow)
-  (let ((str (gensym)) (datatype (gensym)) (restdata (gensym)))
+  (let ((str (gensym)) (datatype (gensym)) (restdata (gensym)) (n (gensym)))
     `(let* ((,str ,seq)
 	    (,datatype (char ,str 0))
 	    (,restdata (subseq ,str 1)))
        (ecase ,datatype
 	 (#\T (if ,table-allow 'table (error "table not allowed")))
-	 (#\N (parse-float ,restdata))
+	 (#\N (let ((,n (parse-float ,restdata :type 'real)))
+		(if (typep ,n 'ratio) (coerce ,n 'float) ,n)))
 	 (#\B (ecase (parse-integer ,restdata)
 		(0 t)
 		(1 nil)))
@@ -46,7 +47,9 @@
 		      (read-table stream restype)
 		      vt)))
 	 (case restype
-	   (:alist (push (cons kv vv) ht))
+	   (:alist (let ((c (assoc kv ht :test #'equal)))
+		     (if c (setf (cdr c) vv)
+			 (push (cons kv vv) ht))))
 	   (otherwise (setf (gethash kv ht) vv))))))))
 
 (defun from-stream (stream restype)