diff --git a/bot.py b/bot.py
index 231bc3e..e2e6185 100644
--- a/bot.py
+++ b/bot.py
@@ -163,7 +163,7 @@ def run_cycle(config: Config) -> bool:
 
     try:
         cooled_down = {
-            pair for pair in portfolio._cooldowns
+            pair for pair in list(portfolio._cooldowns)
             if portfolio.on_cooldown(pair, config.sold_cooldown_hours)
         }
         opportunities = scanner.scan(exclude_pairs=portfolio.open_pairs() | cooled_down)