diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 37ccfde9..51254983 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -34,7 +34,7 @@ jobs:
             # sync MSRV with docs: guide/src/guide/installation.md and Cargo.toml
             rust: 1.60.0
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: Install Rust
       run: bash ci/install-rust.sh ${{ matrix.rust }}
     - name: Build and run tests
@@ -46,7 +46,7 @@ jobs:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v3
     - name: Install Rust
       run: rustup update stable && rustup default stable && rustup component add rustfmt
     - run: cargo fmt --check
diff --git a/guide/src/format/theme/README.md b/guide/src/format/theme/README.md
index 1aeb6dc7..23da5a04 100644
--- a/guide/src/format/theme/README.md
+++ b/guide/src/format/theme/README.md
@@ -1,6 +1,6 @@
 # Theme
 
-The default renderer uses a [handlebars](http://handlebarsjs.com/) template to
+The default renderer uses a [handlebars](https://handlebarsjs.com) template to
 render your markdown files and comes with a default theme included in the mdBook
 binary.
 
diff --git a/src/config.rs b/src/config.rs
index 0c367d84..1a30c507 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -308,7 +308,7 @@ impl<'de> serde::Deserialize<'de> for Config {
             warn!("`description` under a table called `[book]`, move the `destination` entry");
             warn!("from `[output.html]`, renamed to `build-dir`, under a table called");
             warn!("`[build]`, and it should all work.");
-            warn!("Documentation: http://rust-lang.github.io/mdBook/format/config.html");
+            warn!("Documentation: https://rust-lang.github.io/mdBook/format/config.html");
             return Ok(Config::from_legacy(raw));
         }
 
diff --git a/src/theme/book.js b/src/theme/book.js
index e303ebb4..f2516be7 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -68,7 +68,7 @@ function playground_text(playground, hidden = true) {
     }
 
     // updates the visibility of play button based on `no_run` class and
-    // used crates vs ones available on http://play.rust-lang.org
+    // used crates vs ones available on https://play.rust-lang.org
     function update_play_button(pre_block, playground_crates) {
         var play_button = pre_block.querySelector(".play-button");
 
diff --git a/src/theme/tomorrow-night.css b/src/theme/tomorrow-night.css
index 5b4aca77..81fe276e 100644
--- a/src/theme/tomorrow-night.css
+++ b/src/theme/tomorrow-night.css
@@ -1,7 +1,7 @@
 /* Tomorrow Night Theme */
-/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
+/* https://github.com/jmblog/color-themes-for-highlightjs */
 /* Original theme - https://github.com/chriskempson/tomorrow-theme */
-/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
+/* https://github.com/jmblog/color-themes-for-highlightjs */
 
 /* Tomorrow Comment */
 .hljs-comment {
diff --git a/test_book/src/individual/image.md b/test_book/src/individual/image.md
index c73db95a..8bb66d33 100644
--- a/test_book/src/individual/image.md
+++ b/test_book/src/individual/image.md
@@ -4,19 +4,19 @@ For copyright and trademark information on these images, please check [rust-artw
 
 ## A 16x16 image
 
-![16x16 rust-lang logo](http://rust-lang.org/logos/rust-logo-16x16.png)
+![16x16 rust-lang logo](https://rust-lang.org/logos/rust-logo-16x16.png)
 
 ## A 32x32 image
 
-![32x32 rust-lang logo](http://rust-lang.org/logos/rust-logo-32x32-blk.png)
+![32x32 rust-lang logo](https://rust-lang.org/logos/rust-logo-32x32-blk.png)
 
 ## A 256x256 image
 
-![256x256 rust-lang logo](http://rust-lang.org/logos/rust-logo-256x256.png)
+![256x256 rust-lang logo](https://rust-lang.org/logos/rust-logo-256x256.png)
 
 ## A 512x512 image
 
-![512x512 rust-lang logo](http://rust-lang.org/logos/rust-logo-512x512-blk.png)
+![512x512 rust-lang logo](https://rust-lang.org/logos/rust-logo-512x512-blk.png)
 
 ## A large image
 
diff --git a/test_book/src/individual/mixed.md b/test_book/src/individual/mixed.md
index e9d101b2..10b487a0 100644
--- a/test_book/src/individual/mixed.md
+++ b/test_book/src/individual/mixed.md
@@ -31,7 +31,7 @@ fn main(){
 
 A random image sprinkled in between
 
-![16x16 rust-lang logo](http://rust-lang.org/logos/rust-logo-16x16.png)
+![16x16 rust-lang logo](https://rust-lang.org/logos/rust-logo-16x16.png)
 
 ---