diff --git a/CHANGELOG.md b/CHANGELOG.md
index 93d4e31b..8fba505c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased] - ReleaseDate
 ### Fixed
 - supervisor: deadlock if a router returns `Outcome::Multicast` ([#105]).
+- supervisor: print the system config, not only the custom one.
 
 [#105]: https://github.com/elfo-rs/elfo/pull/105
 
diff --git a/elfo-core/src/config.rs b/elfo-core/src/config.rs
index a408bd1d..98e906dc 100644
--- a/elfo-core/src/config.rs
+++ b/elfo-core/src/config.rs
@@ -156,7 +156,7 @@ impl<'de> Deserializer<'de> for AnyConfig {
 
 // === SystemConfig ===
 
-#[derive(Default, Deserialize)]
+#[derive(Debug, Default, Deserialize)]
 #[serde(default)]
 pub(crate) struct SystemConfig {
     pub(crate) logging: crate::logging::LoggingConfig,
diff --git a/elfo-core/src/dumping/config.rs b/elfo-core/src/dumping/config.rs
index 9c391e49..f8503c41 100644
--- a/elfo-core/src/dumping/config.rs
+++ b/elfo-core/src/dumping/config.rs
@@ -1,6 +1,6 @@
 use serde::Deserialize;
 
-#[derive(Clone, Deserialize)]
+#[derive(Debug, Clone, Deserialize)]
 #[serde(default)]
 pub(crate) struct DumpingConfig {
     pub(crate) disabled: bool,
diff --git a/elfo-core/src/logging/config.rs b/elfo-core/src/logging/config.rs
index ca2d623b..070f0fee 100644
--- a/elfo-core/src/logging/config.rs
+++ b/elfo-core/src/logging/config.rs
@@ -1,7 +1,7 @@
 use serde::{Deserialize, Deserializer};
 use tracing::level_filters::LevelFilter;
 
-#[derive(Deserialize)]
+#[derive(Debug, Deserialize)]
 #[serde(default)]
 pub(crate) struct LoggingConfig {
     #[serde(deserialize_with = "deserialize_level_filter")]
diff --git a/elfo-core/src/supervisor.rs b/elfo-core/src/supervisor.rs
index 0d801315..aef1bae7 100644
--- a/elfo-core/src/supervisor.rs
+++ b/elfo-core/src/supervisor.rs
@@ -426,7 +426,14 @@ where
         control.user_config = Some(config.get_user::<C>().clone());
         self.router
             .update(control.user_config.as_ref().expect("just saved"));
-        self.in_scope(|| info!(config = ?control.user_config.as_ref().unwrap(), "router updated"));
+
+        self.in_scope(|| {
+            debug!(
+                message = "config updated",
+                system = ?control.system_config,
+                custom = ?control.user_config.as_ref().unwrap(),
+            )
+        });
     }
 
     fn subscribe_to_statuses(&self, addr: Addr, forcing: bool) {
diff --git a/elfo-core/src/telemetry/config.rs b/elfo-core/src/telemetry/config.rs
index 852862ac..5780f11c 100644
--- a/elfo-core/src/telemetry/config.rs
+++ b/elfo-core/src/telemetry/config.rs
@@ -1,10 +1,12 @@
+use std::fmt;
+
 use regex::Regex;
 use serde::{
     de::{Deserializer, Error},
     Deserialize,
 };
 
-#[derive(Deserialize)]
+#[derive(Debug, Deserialize)]
 #[serde(default)]
 pub(crate) struct TelemetryConfig {
     pub(crate) per_actor_group: bool,
@@ -16,6 +18,19 @@ pub(crate) enum PerActorKey {
     Replacement(Regex, String),
 }
 
+impl fmt::Debug for PerActorKey {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Bool(flag) => write!(f, "{:?}", flag),
+            Self::Replacement(pattern, template) => f
+                .debug_tuple("")
+                .field(&pattern.as_str())
+                .field(&template)
+                .finish(),
+        }
+    }
+}
+
 impl PerActorKey {
     pub(crate) fn is_enabled(&self) -> bool {
         match self {