diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 29c686e5d0853..79363c3a5ca5c 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -1925,9 +1925,7 @@ impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
             return;
         }
 
-        TAG_NOT_ROOT.hash_stable(ctx, hasher);
         let index = self.as_u32() as usize;
-
         let res = CACHE.with(|cache| cache.borrow().get(index).copied().flatten());
 
         if let Some(res) = res {
@@ -1936,6 +1934,7 @@ impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
             let new_len = index + 1;
 
             let mut sub_hasher = StableHasher::new();
+            TAG_NOT_ROOT.hash_stable(ctx, &mut sub_hasher);
             self.expn_data().hash_stable(ctx, &mut sub_hasher);
             let sub_hash: Fingerprint = sub_hasher.finish();