diff --git a/redbot/cogs/mod/mod.py b/redbot/cogs/mod/mod.py
index 837b49ea8..6b4a192d7 100644
--- a/redbot/cogs/mod/mod.py
+++ b/redbot/cogs/mod/mod.py
@@ -1397,7 +1397,7 @@ class Mod(commands.Cog):
         while self == self.bot.get_cog("Mod"):
             for guild in self.bot.guilds:
                 async with self.settings.guild(guild).current_tempbans() as guild_tempbans:
-                    for uid in guild_tempbans:
+                    for uid in guild_tempbans.copy():
                         unban_time = datetime.utcfromtimestamp(
                             await self.settings.member(member(uid, guild)).banned_until()
                         )