diff --git a/src/Discord.Net.Rest/API/Common/GuildMember.cs b/src/Discord.Net.Rest/API/Common/GuildMember.cs
index 19bdd6a9..48542d55 100644
--- a/src/Discord.Net.Rest/API/Common/GuildMember.cs
+++ b/src/Discord.Net.Rest/API/Common/GuildMember.cs
@@ -14,7 +14,7 @@ namespace Discord.API
         [JsonProperty("roles")]
         public Optional<ulong[]> Roles { get; set; }
         [JsonProperty("joined_at")]
-        public Optional<DateTimeOffset> JoinedAt { get; set; }
+        public Optional<DateTimeOffset?> JoinedAt { get; set; }
         [JsonProperty("deaf")]
         public Optional<bool> Deaf { get; set; }
         [JsonProperty("mute")]
diff --git a/src/Discord.Net.Rest/Entities/Users/RestGuildUser.cs b/src/Discord.Net.Rest/Entities/Users/RestGuildUser.cs
index c12f1c18..b37d4343 100644
--- a/src/Discord.Net.Rest/Entities/Users/RestGuildUser.cs
+++ b/src/Discord.Net.Rest/Entities/Users/RestGuildUser.cs
@@ -109,7 +109,7 @@ namespace Discord.Rest
         {
             base.Update(model.User);
             if (model.JoinedAt.IsSpecified)
-                _joinedAtTicks = model.JoinedAt.Value.UtcTicks;
+                _joinedAtTicks = model.JoinedAt.Value.GetValueOrDefault(DateTimeOffset.UtcNow).UtcTicks;
             if (model.Nick.IsSpecified)
                 Nickname = model.Nick.Value;
             if (model.Avatar.IsSpecified)
diff --git a/src/Discord.Net.WebSocket/Entities/Users/SocketGuildUser.cs b/src/Discord.Net.WebSocket/Entities/Users/SocketGuildUser.cs
index ed735429..0a79b770 100644
--- a/src/Discord.Net.WebSocket/Entities/Users/SocketGuildUser.cs
+++ b/src/Discord.Net.WebSocket/Entities/Users/SocketGuildUser.cs
@@ -178,7 +178,7 @@ namespace Discord.WebSocket
         {
             base.Update(state, model.User);
             if (model.JoinedAt.IsSpecified)
-                _joinedAtTicks = model.JoinedAt.Value.UtcTicks;
+                _joinedAtTicks = model.JoinedAt.Value.GetValueOrDefault(DateTimeOffset.UtcNow).UtcTicks;
             if (model.Nick.IsSpecified)
                 Nickname = model.Nick.Value;
             if (model.Avatar.IsSpecified)