diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0f16918c..1a1aeea2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,7 +17,7 @@ This is the rolling changelog for TShock for Terraria. Use past tense when addin
  * `/v2/server/rawcmd` (@WhiteXZ).
 * Fixed `/user group` always giving an unhelpful error messaging telling you to check the console, even if we knew exactly why it failed (@nicatronTg).
 * Removed _all obsolete methods in TShock marked obsolete prior to this version (all of them)_ (@nicatronTg).
-* Fixed issue where registration + login would fail with no pre-existing users (@DogooFalchion).
+* Fixed issue where registration + login would fail because KnownIps had 0 items and .Last() doesn't work on collections with 0 items (@DogooFalchion, @nicatronTg, @Simon311).
 * Added `/uploadssc [player]` which allows someone to upload SSC data for [player] and store it on the server. Adds `tshock.ssc.upload` and `tshock.ssc.upload.others` permission nodes to match (@DogooFalchion).
 * Added hardened stone to the whitelist of tiles editable by players (@DogooFalchion).
 * Added conversion system to send convert old MOTD format into smart text, while preserving initial line starting values to keep byte optimization for background colors Thanks to (@WhiteXZ, @Simon311, and especially @DogooFalchion) for the hard work on this issue.
diff --git a/TShockAPI/TShock.cs b/TShockAPI/TShock.cs
index 9a6aac10..9e459ec2 100755
--- a/TShockAPI/TShock.cs
+++ b/TShockAPI/TShock.cs
@@ -409,16 +409,23 @@ namespace TShockAPI
 				KnownIps = JsonConvert.DeserializeObject<List<String>>(args.Player.User.KnownIps);
 			}
 
-			bool last = KnownIps.Last() == args.Player.IP;
-			if (!last)
+			if (KnownIps.Count == 0)
 			{
-				if (KnownIps.Count == 100)
-				{
-					KnownIps.RemoveAt(0);
-				}
-
 				KnownIps.Add(args.Player.IP);
 			}
+			else
+			{
+				bool last = KnownIps.Last() == args.Player.IP;
+				if (!last)
+				{
+					if (KnownIps.Count == 100)
+					{
+						KnownIps.RemoveAt(0);
+					}
+
+					KnownIps.Add(args.Player.IP);
+				}
+			}
 
 			args.Player.User.KnownIps = JsonConvert.SerializeObject(KnownIps, Formatting.Indented);
 			Users.UpdateLogin(args.Player.User);