diff --git a/OpenTween/Api/DataModel/MastodonAccount.cs b/OpenTween/Api/DataModel/MastodonAccount.cs
index 3dfb2d88b..8a37b74f8 100644
--- a/OpenTween/Api/DataModel/MastodonAccount.cs
+++ b/OpenTween/Api/DataModel/MastodonAccount.cs
@@ -23,6 +23,7 @@
 
 namespace OpenTween.Api.DataModel
 {
+    [DataContract]
     public class MastodonAccount
     {
         [DataMember(Name = "id")]
diff --git a/OpenTween/Api/DataModel/MastodonApplication.cs b/OpenTween/Api/DataModel/MastodonApplication.cs
index 2898f7587..996547997 100644
--- a/OpenTween/Api/DataModel/MastodonApplication.cs
+++ b/OpenTween/Api/DataModel/MastodonApplication.cs
@@ -23,6 +23,7 @@
 
 namespace OpenTween.Api.DataModel
 {
+    [DataContract]
     public class MastodonApplication
     {
         [DataMember(Name = "name")]
diff --git a/OpenTween/Api/DataModel/MastodonAttachment.cs b/OpenTween/Api/DataModel/MastodonAttachment.cs
index 32bba1c18..3738659c1 100644
--- a/OpenTween/Api/DataModel/MastodonAttachment.cs
+++ b/OpenTween/Api/DataModel/MastodonAttachment.cs
@@ -23,6 +23,7 @@
 
 namespace OpenTween.Api.DataModel
 {
+    [DataContract]
     public class MastodonAttachment
     {
         [DataMember(Name = "id")]
diff --git a/OpenTween/Api/DataModel/MastodonMention.cs b/OpenTween/Api/DataModel/MastodonMention.cs
index 3bc1af9dd..36be9b52c 100644
--- a/OpenTween/Api/DataModel/MastodonMention.cs
+++ b/OpenTween/Api/DataModel/MastodonMention.cs
@@ -23,6 +23,7 @@
 
 namespace OpenTween.Api.DataModel
 {
+    [DataContract]
     public class MastodonMention
     {
         [DataMember(Name = "url")]
diff --git a/OpenTween/Api/DataModel/MastodonStatus.cs b/OpenTween/Api/DataModel/MastodonStatus.cs
index 0951ebe87..eff996df8 100644
--- a/OpenTween/Api/DataModel/MastodonStatus.cs
+++ b/OpenTween/Api/DataModel/MastodonStatus.cs
@@ -23,6 +23,7 @@
 
 namespace OpenTween.Api.DataModel
 {
+    [DataContract]
     public class MastodonStatus
     {
         [DataMember(Name = "id")]
@@ -59,10 +60,10 @@ public class MastodonStatus
         public int FavouritesCount { get; set; }
 
         [DataMember(Name = "reblogged")]
-        public bool Reblogged { get; set; }
+        public bool? Reblogged { get; set; }
 
         [DataMember(Name = "favourited")]
-        public bool Favourited { get; set; }
+        public bool? Favourited { get; set; }
 
         [DataMember(Name = "sensitive")]
         public bool? Sensitive { get; set; }
diff --git a/OpenTween/Api/DataModel/MastodonTag.cs b/OpenTween/Api/DataModel/MastodonTag.cs
index 77258710c..d3169f0b8 100644
--- a/OpenTween/Api/DataModel/MastodonTag.cs
+++ b/OpenTween/Api/DataModel/MastodonTag.cs
@@ -23,6 +23,7 @@
 
 namespace OpenTween.Api.DataModel
 {
+    [DataContract]
     public class MastodonTag
     {
         [DataMember(Name = "name")]