diff --git a/json/parser.scm b/json/parser.scm
index 8f71415..8b33a22 100644
--- a/json/parser.scm
+++ b/json/parser.scm
@@ -210,6 +210,12 @@
        ;; Anything other than colon is an error.
        (else (json-exception port))))))
 
+(define (uniquify-keys pairs res)
+  (cond ((null? pairs) res)
+        ((assoc (caar pairs) res)
+         (uniquify-keys (cdr pairs) res))
+        (else (uniquify-keys (cdr pairs) (cons (car pairs) res)))))
+
 (define (json-read-object port null ordered)
   (expect-delimiter port #\{)
   (let loop ((pairs '()) (added #t))
@@ -220,7 +226,9 @@
        ((eqv? ch #\})
         (read-char port)
         (cond
-         (added (if ordered (reverse! pairs) pairs))
+         (added (if ordered
+                    (uniquify-keys pairs '())
+                    (reverse! (uniquify-keys pairs '()))))
          (else (json-exception port))))
        ;; Read one pair and continue.
        ((eqv? ch #\")
diff --git a/tests/test-parser.scm b/tests/test-parser.scm
index f1b2920..380e0ba 100644
--- a/tests/test-parser.scm
+++ b/tests/test-parser.scm
@@ -86,6 +86,7 @@
 (test-error #t (json-string->scm "[,1]"))
 (test-error #t (json-string->scm "[1,2,,,5]"))
 (test-error #t (json-string->scm "[1,2"))
+(test-error #t (json-string->scm "[1,2,]"))
 
 ;; Objects
 (test-equal '() (json-string->scm "{}"))
@@ -102,6 +103,11 @@
 (test-equal '() (json-string->scm "{}" #:ordered #t))
 (test-equal '(("green" . 1) ("eggs" . 2) ("ham" . 3)) (json-string->scm "{\"green\":1, \"eggs\":2, \"ham\":3}" #:ordered #t))
 
+;; Objects with duplicate keys
+(test-equal '(("bar" . 2) ("baz" . #(1 2 3)) ("foo" . "last")) (json-string->scm "{\"foo\": \"first\", \"bar\": 2, \"foo\": \"second\", \"baz\": [1, 2, 3], \"foo\": \"last\"}" #:ordered #t))
+
+(test-equal '(("foo" . "last") ("baz" . #(1 2 3)) ("bar" . 2)) (json-string->scm "{\"foo\": \"first\", \"bar\": 2, \"foo\": \"second\", \"baz\": [1, 2, 3], \"foo\": \"last\"}" ))
+
 ;; Since the following JSON object contains more than one key-value pair, we
 ;; can't use "test-equal" directly since the output could be unordered.
 (define book (json-string->scm "{\"title\":\"A book\",\"author\":\"An author\",\"price\":29.99}"))