diff --git a/src/fns.rs b/src/fns.rs
index 347e24f..92d884a 100644
--- a/src/fns.rs
+++ b/src/fns.rs
@@ -1,3 +1,5 @@
+//! Functions used to make metrics.
+
 use crate::mathx::FloatExt2;
 
 pub trait Limiter {
diff --git a/src/utils.rs b/src/utils.rs
index 5e7e33a..a097764 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,3 +1,5 @@
+//! Utility functions to work with metrics.
+
 use crate::{
 	mathx::MatExt as _,
 	riemann::{trace_iter, Metric},