diff --git a/src/librustc_trans/diagnostics.rs b/src/librustc_trans/diagnostics.rs
index dd7c3834e564..05236a7a6fb2 100644
--- a/src/librustc_trans/diagnostics.rs
+++ b/src/librustc_trans/diagnostics.rs
@@ -12,6 +12,21 @@
 
 register_long_diagnostics! {
 
+E0515: r##"
+A constant index expression was out of bounds. Erroneous code example:
+
+```
+let x = &[0, 1, 2][7]; // error: const index-expr is out of bounds
+```
+
+Please specify a valid index (not inferior to 0 or superior to array length).
+Example:
+
+```
+let x = &[0, 1, 2][2]; // ok!
+```
+"##,
+
 }
 
 register_diagnostics! {