diff --git a/Cargo.toml b/Cargo.toml
index 4e0d51d4..9509250c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -96,6 +96,7 @@ used_underscore_binding = "warn"
 verbose_file_reads = "warn"
 wildcard_dependencies = "warn"
 wildcard_imports = "warn"
+zero_sized_map_values = "warn"
 
 [package]
 name = "grapevine"
diff --git a/src/config.rs b/src/config.rs
index 8e512a49..ee861693 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -80,6 +80,8 @@ pub(crate) struct Config {
     pub(crate) emergency_password: Option<String>,
 
     #[serde(flatten)]
+    // This has special meaning to `serde`
+    #[allow(clippy::zero_sized_map_values)]
     pub(crate) catchall: BTreeMap<String, IgnoredAny>,
 }