diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index bd2a0139de99..b5d843822ff7 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1205,7 +1205,7 @@ impl<'a> Parser<'a> {
     }
 
     fn mk_expr_tuple_field_access(
-        &mut self,
+        &self,
         lo: Span,
         ident_span: Span,
         base: P<Expr>,