diff --git a/CHANGELOG.md b/CHANGELOG.md
index 46cf14177c..e191fafb5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,9 @@ however, insignificant breaking changes do not guarantee a major version bump, s
 ### Changed
 - Repo moved to https://github.com/modmail-dev/modmail.
 
+### Internal
+- `ConfigManager.get` no longer accepts two positional arguments: the `convert` argument is now keyword-only.
+
 # v4.0.2
 
 ### Breaking
diff --git a/cogs/plugins.py b/cogs/plugins.py
index f225d90caa..4fb8341c70 100644
--- a/cogs/plugins.py
+++ b/cogs/plugins.py
@@ -302,10 +302,10 @@ async def parse_user_input(self, ctx, plugin_name, check_version=False):
             plugin = Plugin(user, repo, plugin_name, branch)
 
         else:
-            if not self.bot.config.get("registry_plugins_only", False):
+            if self.bot.config.get("registry_plugins_only"):
                 embed = discord.Embed(
-                    description="This plugin is not in the registry. "
-                    "To install it, you must set `REGISTRY_PLUGINS_ONLY=false` in your .env file or config settings.",
+                    description="This plugin is not in the registry. To install this plugin, "
+                                "you must set `REGISTRY_PLUGINS_ONLY=no` or remove this key in your .env file.",
                     color=self.bot.error_color,
                 )
                 await ctx.send(embed=embed)
diff --git a/core/config.py b/core/config.py
index 9a033167b7..9476352573 100644
--- a/core/config.py
+++ b/core/config.py
@@ -301,7 +301,7 @@ def __getitem__(self, key: str) -> typing.Any:
     def __delitem__(self, key: str) -> None:
         return self.remove(key)
 
-    def get(self, key: str, convert=True) -> typing.Any:
+    def get(self, key: str, *, convert: bool = True) -> typing.Any:
         key = key.lower()
         if key not in self.all_keys:
             raise InvalidConfigError(f'Configuration "{key}" is invalid.')