diff --git a/book/src/01_calculator/calc_intro.md b/book/src/01_calculator/calc_intro.md
index 1992848..2858516 100644
--- a/book/src/01_calculator/calc_intro.md
+++ b/book/src/01_calculator/calc_intro.md
@@ -7,7 +7,7 @@ If you haven't cloned the [GitHub](https://github.com/ehsanmok/create-your-own-l
 To start, we have `1 + 1;` in [examples/simple.calc](https://github.com/ehsanmok/create-your-own-lang-with-rust/blob/master/calculator/examples/simple.calc) where you can compile with
 
 ```text
-cargo build --bin main // create a simple executable for Calc
+cargo build --bin main # create a simple executable for Calc
 ../target/debug/main examples/simple.calc
 ```