diff --git a/payphone/cogs/calls/cog.py b/payphone/cogs/calls/cog.py
index 339bb43..a764e8f 100644
--- a/payphone/cogs/calls/cog.py
+++ b/payphone/cogs/calls/cog.py
@@ -32,6 +32,7 @@ class Calls(base.Cog):
 
         self.flush_messages.add_exception_type(exceptions.ConfigurationError)
         self.flush_messages.add_exception_type(TypeError)
+        self.flush_messages.add_exception_type(RuntimeError)
         self.flush_messages.start()
 
     def cog_unload(self) -> None: