diff --git a/src/doc/intro.md b/src/doc/intro.md
index 21ec551eb30..14c1f87fc1b 100644
--- a/src/doc/intro.md
+++ b/src/doc/intro.md
@@ -471,7 +471,7 @@ fn main() {
         spawn(proc() {
             let mut array = number.lock();
 
-            (*(*array).get_mut(i)) += 1;
+            (*array)[i] += 1;
 
             println!("numbers[{}] is {}", i, (*array)[i]);
         });