diff --git a/README.md b/README.md
index 85dc8f8..365042f 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ To discuss and/or collaborate with other Rust developers, join our [Discord comm
 ```shell
 git clone git@github.com:letsgetrusty/rust-learning-guide.git
 
-cargo install mdbook
+cargo install mdbook --version 0.4.36
 
 cd rust-learning-guide && mdbook serve --open
 ```
diff --git a/src/beginner/control-flow.md b/src/beginner/control-flow.md
index e601aa7..c05a9af 100644
--- a/src/beginner/control-flow.md
+++ b/src/beginner/control-flow.md
@@ -16,6 +16,10 @@ pub fn bigger(a: i32, b: i32) -> i32 {
     // - additional variables
 }
 
+fn main() {
+    print!("{} is bigger than {}", bigger(10, 8), 8);
+}
+
 // Don't mind this for now :)
 #[cfg(test)]
 mod tests {
@@ -45,6 +49,10 @@ pub fn bigger(a: i32, b: i32) -> i32 {
     }
 }
 
+fn main() {
+    print!("{} is bigger than {}", bigger(10, 8), 8);
+}
+
 // Don't mind this for now :)
 #[cfg(test)]
 mod tests {