diff --git a/test/Nancy.Tests/Unit/Json/Simple/NancySerializationStrategyFixture.cs b/test/Nancy.Tests/Unit/Json/Simple/NancySerializationStrategyFixture.cs
index 59550d8549..314923f293 100644
--- a/test/Nancy.Tests/Unit/Json/Simple/NancySerializationStrategyFixture.cs
+++ b/test/Nancy.Tests/Unit/Json/Simple/NancySerializationStrategyFixture.cs
@@ -92,7 +92,8 @@ public void Should_serialize_unspecified_datetime_object()
 
             //Then
             canSerialize.ShouldBeTrue();
-            serializedObject.ShouldEqual(string.Format("2014-03-09T17:03:25.2340000+{0}", offset.Hours.ToString("00") + ":" + offset.Minutes.ToString("00")));
+            serializedObject.ShouldEqual(string.Format("2014-03-09T17:03:25.2340000{0}:{1}", 
+                offset.Hours.ToString("+00;-00"), offset.Minutes.ToString("00")));
         }
 
         [Fact]
@@ -109,7 +110,8 @@ public void Should_serialize_local_datetime_object()
 
             //Then
             canSerialize.ShouldBeTrue();
-            serializedObject.ShouldEqual(string.Format("2014-03-09T17:03:25.2340000+{0}", offset.Hours.ToString("00") + ":" + offset.Minutes.ToString("00")));
+            serializedObject.ShouldEqual(string.Format("2014-03-09T17:03:25.2340000{0}:{1}",
+                offset.Hours.ToString("+00;-00"), offset.Minutes.ToString("00")));
         }
 
         [Fact]