diff --git a/actix-settings/src/lib.rs b/actix-settings/src/lib.rs
index 55742f7e2..7185c9273 100644
--- a/actix-settings/src/lib.rs
+++ b/actix-settings/src/lib.rs
@@ -1,5 +1,12 @@
 //! Easily manage Actix Web's settings from a TOML file and environment variables.
 
+#![forbid(unsafe_code)]
+#![deny(rust_2018_idioms, nonstandard_style)]
+#![warn(future_incompatible, missing_debug_implementations)]
+// #![warn(missing_docs)]
+#![doc(html_logo_url = "https://actix.rs/img/logo.png")]
+#![doc(html_favicon_url = "https://actix.rs/favicon.ico")]
+
 use std::{
     env, fmt,
     fs::File,
diff --git a/actix-settings/src/settings/backlog.rs b/actix-settings/src/settings/backlog.rs
index 5e4eecdef..55b75be60 100644
--- a/actix-settings/src/settings/backlog.rs
+++ b/actix-settings/src/settings/backlog.rs
@@ -35,7 +35,7 @@ impl<'de> de::Deserialize<'de> for Backlog {
         impl<'de> de::Visitor<'de> for BacklogVisitor {
             type Value = Backlog;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 let msg = "Either \"default\" or a string containing an integer > 0";
                 formatter.write_str(msg)
             }
diff --git a/actix-settings/src/settings/keep_alive.rs b/actix-settings/src/settings/keep_alive.rs
index 55e7d0893..5b17d89b2 100644
--- a/actix-settings/src/settings/keep_alive.rs
+++ b/actix-settings/src/settings/keep_alive.rs
@@ -31,7 +31,7 @@ impl Parse for KeepAlive {
             };
         }
 
-        let digits_in = |m: regex::Match| &string[m.start()..m.end()];
+        let digits_in = |m: regex::Match<'_>| &string[m.start()..m.end()];
         match string {
             "default" => Ok(KeepAlive::Default),
             "disabled" => Ok(KeepAlive::Disabled),
@@ -58,7 +58,7 @@ impl<'de> de::Deserialize<'de> for KeepAlive {
         impl<'de> de::Visitor<'de> for KeepAliveVisitor {
             type Value = KeepAlive;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 let msg = "Either \"default\", \"disabled\", \"os\", or a string of the format \"N seconds\" where N is an integer > 0";
                 formatter.write_str(msg)
             }
diff --git a/actix-settings/src/settings/max_connection_rate.rs b/actix-settings/src/settings/max_connection_rate.rs
index 029daba7f..7647594ca 100644
--- a/actix-settings/src/settings/max_connection_rate.rs
+++ b/actix-settings/src/settings/max_connection_rate.rs
@@ -35,7 +35,7 @@ impl<'de> de::Deserialize<'de> for MaxConnectionRate {
         impl<'de> de::Visitor<'de> for MaxConnectionRateVisitor {
             type Value = MaxConnectionRate;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 let msg = "Either \"default\" or a string containing an integer > 0";
                 formatter.write_str(msg)
             }
diff --git a/actix-settings/src/settings/max_connections.rs b/actix-settings/src/settings/max_connections.rs
index b50ba3aeb..98cd0c7eb 100644
--- a/actix-settings/src/settings/max_connections.rs
+++ b/actix-settings/src/settings/max_connections.rs
@@ -35,7 +35,7 @@ impl<'de> de::Deserialize<'de> for MaxConnections {
         impl<'de> de::Visitor<'de> for MaxConnectionsVisitor {
             type Value = MaxConnections;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 let msg = "Either \"default\" or a string containing an integer > 0";
                 formatter.write_str(msg)
             }
diff --git a/actix-settings/src/settings/mode.rs b/actix-settings/src/settings/mode.rs
index a590106bd..3833da38a 100644
--- a/actix-settings/src/settings/mode.rs
+++ b/actix-settings/src/settings/mode.rs
@@ -2,11 +2,14 @@ use serde::Deserialize;
 
 use crate::{AtResult, Parse};
 
-///
+/// Marker of intended deployment environment.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum Mode {
+    /// Marks development environment.
     Development,
+
+    /// Marks production environment.
     Production,
 }
 
diff --git a/actix-settings/src/settings/num_workers.rs b/actix-settings/src/settings/num_workers.rs
index a0d6755bb..2b15ed6e8 100644
--- a/actix-settings/src/settings/num_workers.rs
+++ b/actix-settings/src/settings/num_workers.rs
@@ -35,7 +35,7 @@ impl<'de> de::Deserialize<'de> for NumWorkers {
         impl<'de> de::Visitor<'de> for NumWorkersVisitor {
             type Value = NumWorkers;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 let msg = "Either \"default\" or a string containing an integer > 0";
                 formatter.write_str(msg)
             }
diff --git a/actix-settings/src/settings/timeout.rs b/actix-settings/src/settings/timeout.rs
index 6661c381d..12c03ac6d 100644
--- a/actix-settings/src/settings/timeout.rs
+++ b/actix-settings/src/settings/timeout.rs
@@ -64,7 +64,7 @@ impl<'de> de::Deserialize<'de> for Timeout {
         impl<'de> de::Visitor<'de> for TimeoutVisitor {
             type Value = Timeout;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 let msg = "Either \"default\", \"disabled\", \"os\", or a string of the format \"N seconds\" where N is an integer > 0";
                 formatter.write_str(msg)
             }