diff --git a/redbot/cogs/filter/filter.py b/redbot/cogs/filter/filter.py
index fae8cab8e..e81494234 100644
--- a/redbot/cogs/filter/filter.py
+++ b/redbot/cogs/filter/filter.py
@@ -286,6 +286,10 @@ class Filter(commands.Cog):
     def invalidate_cache(self, guild: discord.Guild, channel: discord.TextChannel = None):
         """ Invalidate a cached pattern"""
         self.pattern_cache.pop((guild, channel), None)
+        if channel is None:
+            for keyset in list(self.pattern_cache.keys()):  # cast needed, no remove
+                if guild in keyset:
+                    self.pattern_cache.pop(keyset, None)
 
     async def add_to_filter(
         self, server_or_channel: Union[discord.Guild, discord.TextChannel], words: list