diff --git a/crates/proc_macro_srv/src/rustc_server.rs b/crates/proc_macro_srv/src/rustc_server.rs
index a8504f762e9..952b4a97fbb 100644
--- a/crates/proc_macro_srv/src/rustc_server.rs
+++ b/crates/proc_macro_srv/src/rustc_server.rs
@@ -14,7 +14,6 @@ use std::collections::HashMap;
 use std::hash::Hash;
 use std::iter::FromIterator;
 use std::ops::Bound;
-use std::str::FromStr;
 use std::{ascii, vec::IntoIter};
 
 type Group = tt::Subtree;
@@ -278,6 +277,42 @@ impl server::FreeFunctions for Rustc {
     }
 }
 
+fn subtree_replace_token_ids_with_unspecified(subtree: tt::Subtree) -> tt::Subtree {
+    tt::Subtree {
+        delimiter: subtree.delimiter.map(|d| tt::Delimiter { id: tt::TokenId::unspecified(), ..d }),
+        token_trees: subtree
+            .token_trees
+            .into_iter()
+            .map(|t| token_tree_replace_token_ids_with_unspecified(t))
+            .collect(),
+    }
+}
+
+fn token_tree_replace_token_ids_with_unspecified(tt: tt::TokenTree) -> tt::TokenTree {
+    match tt {
+        tt::TokenTree::Leaf(leaf) => {
+            tt::TokenTree::Leaf(leaf_replace_token_ids_with_unspecified(leaf))
+        }
+        tt::TokenTree::Subtree(subtree) => {
+            tt::TokenTree::Subtree(subtree_replace_token_ids_with_unspecified(subtree))
+        }
+    }
+}
+
+fn leaf_replace_token_ids_with_unspecified(leaf: tt::Leaf) -> tt::Leaf {
+    match leaf {
+        tt::Leaf::Literal(lit) => {
+            tt::Leaf::Literal(tt::Literal { id: tt::TokenId::unspecified(), ..lit })
+        }
+        tt::Leaf::Punct(punct) => {
+            tt::Leaf::Punct(tt::Punct { id: tt::TokenId::unspecified(), ..punct })
+        }
+        tt::Leaf::Ident(ident) => {
+            tt::Leaf::Ident(tt::Ident { id: tt::TokenId::unspecified(), ..ident })
+        }
+    }
+}
+
 impl server::TokenStream for Rustc {
     fn new(&mut self) -> Self::TokenStream {
         Self::TokenStream::new()
@@ -287,7 +322,8 @@ impl server::TokenStream for Rustc {
         stream.is_empty()
     }
     fn from_str(&mut self, src: &str) -> Self::TokenStream {
-        Self::TokenStream::from_str(src).expect("cannot parse string")
+        let (subtree, _) = mbe::parse_to_token_tree(src).expect("cannot parse string");
+        TokenStream::with_subtree(subtree_replace_token_ids_with_unspecified(subtree))
     }
     fn to_string(&mut self, stream: &Self::TokenStream) -> String {
         stream.to_string()