diff --git a/src/convert/config.rs b/src/convert/config.rs
index bf37514..e88ae5a 100644
--- a/src/convert/config.rs
+++ b/src/convert/config.rs
@@ -1,3 +1,18 @@
+//! Convert [`config::ConfigError`] into [`AppError`],
+//! producing [`AppErrorKind::Config`].
+//!
+//! Enabled with the `config` feature.
+//!
+//! ## Example
+//!
+//! ```rust,ignore
+//! use config::ConfigError;
+//! use masterror::{AppError, AppErrorKind};
+//!
+//! let err = ConfigError::Message("missing key".into());
+//! let app_err: AppError = err.into();
+//! assert!(matches!(app_err.kind, AppErrorKind::Config));
+//! ```
 #[cfg(feature = "config")]
 use config::ConfigError;
 
@@ -5,8 +20,23 @@ use config::ConfigError;
 use crate::AppError;
 
 #[cfg(feature = "config")]
+#[cfg_attr(docsrs, doc(cfg(feature = "config")))]
 impl From<ConfigError> for AppError {
     fn from(err: ConfigError) -> Self {
         AppError::config(err.to_string())
     }
 }
+
+#[cfg(all(test, feature = "config"))]
+mod tests {
+    use config::ConfigError;
+
+    use crate::{AppError, AppErrorKind};
+
+    #[test]
+    fn maps_to_config_kind() {
+        let err = ConfigError::Message("dummy".into());
+        let app_err = AppError::from(err);
+        assert!(matches!(app_err.kind, AppErrorKind::Config));
+    }
+}