diff --git a/src/librustc_codegen_llvm/diagnostics.rs b/src/librustc_codegen_llvm/diagnostics.rs
index 05359f62ac03..668d602a69c2 100644
--- a/src/librustc_codegen_llvm/diagnostics.rs
+++ b/src/librustc_codegen_llvm/diagnostics.rs
@@ -56,7 +56,7 @@ assembly call.
 
 In particular, it can happen if you forgot the closing bracket of a register
 constraint (see issue #51430):
-```
+```compile_fail
 #![feature(asm)]
 
 fn main() {