diff --git a/core/src/ffi/c_str.rs b/core/src/ffi/c_str.rs
index bd2b2c36c..07b11814f 100644
--- a/core/src/ffi/c_str.rs
+++ b/core/src/ffi/c_str.rs
@@ -79,9 +79,9 @@ use crate::str;
 ///
 /// [str]: prim@str "str"
 #[derive(Hash)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "CStr")]
 #[stable(feature = "core_c_str", since = "1.64.0")]
 #[rustc_has_incoherent_inherent_impls]
+#[cfg_attr(not(bootstrap), lang = "CStr")]
 // FIXME:
 // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies
 // on `CStr` being layout-compatible with `[u8]`.
diff --git a/proc_macro/src/bridge/mod.rs b/proc_macro/src/bridge/mod.rs
index 54b11c543..caecda1bc 100644
--- a/proc_macro/src/bridge/mod.rs
+++ b/proc_macro/src/bridge/mod.rs
@@ -337,6 +337,8 @@ pub enum LitKind {
     StrRaw(u8),
     ByteStr,
     ByteStrRaw(u8),
+    CStr,
+    CStrRaw(u8),
     Err,
 }
 
@@ -350,6 +352,8 @@ rpc_encode_decode!(
         StrRaw(n),
         ByteStr,
         ByteStrRaw(n),
+        CStr,
+        CStrRaw(n),
         Err,
     }
 );