diff --git a/lib/src/util.dart b/lib/src/util.dart
index ae73a7d..9316572 100644
--- a/lib/src/util.dart
+++ b/lib/src/util.dart
@@ -88,9 +88,10 @@ class JsonObject {
       case Uri:
         return Uri.parse(v) as T;
       case DateTime:
-        return DateTime.fromMillisecondsSinceEpoch(v * 1000) as T;
+        return DateTime.fromMillisecondsSinceEpoch(((v as num).round() * 1000))
+            as T;
       case Duration:
-        return Duration(seconds: v) as T;
+        return Duration(seconds: (v as num).round()) as T;
       case String:
       case num:
       case bool:
diff --git a/test/jwt_test.dart b/test/jwt_test.dart
index 2b3ecc6..d9a0f02 100644
--- a/test/jwt_test.dart
+++ b/test/jwt_test.dart
@@ -1,6 +1,6 @@
-import 'package:test/test.dart';
-import 'package:jose/src/jwt.dart';
 import 'package:jose/src/jwk.dart';
+import 'package:jose/src/jwt.dart';
+import 'package:test/test.dart';
 
 void main() {
   group('JWT Examples from RFC7519', () {
@@ -153,4 +153,9 @@ void main() {
           'AVO9iT5AV4CzvDJCdhSFlQ');
     });
   });
+
+  test('JsonWebTokenClaims can handle doubles in expiration', () {
+    final claims = JsonWebTokenClaims.fromJson({'exp': 1300819380.0});
+    expect(claims.expiry, DateTime.fromMillisecondsSinceEpoch(1300819380000));
+  });
 }