diff --git a/src/items.md b/src/items.md
index 912fba031..280378c90 100644
--- a/src/items.md
+++ b/src/items.md
@@ -416,6 +416,7 @@ modifier.
 extern fn new_i32() -> i32 { 0 }
 
 // Declares an extern fn with "stdcall" ABI
+# #[cfg(target_arch = "x86_64")]
 extern "stdcall" fn new_i32_stdcall() -> i32 { 0 }
 ```