diff --git a/src/start/panicking.md b/src/start/panicking.md
index 10f7318b..a1365fa8 100644
--- a/src/start/panicking.md
+++ b/src/start/panicking.md
@@ -87,7 +87,7 @@ use cortex_m_rt::entry;
 #[entry]
 fn main() -> ! {
     let xs = [0, 1, 2];
-    let i = xs.len() + 1;
+    let i = xs.len();
     let _y = xs[i]; // out of bounds access
 
     loop {}