diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 2f9684e332..4c67921bd6 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -55,6 +55,13 @@ pub use self::{
 
 pub use self::function::FnSignatureInfo;
 
+/// An `MFileId` is like a `FileId`, but it can also refer to code generated by
+/// macros.
+pub enum MFileId {
+    File(FileId),
+    Macro(MacroCallId),
+}
+
 /// Def's are a core concept of hir. A `Def` is an Item (function, module, etc)
 /// in a specific module.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]