diff --git a/src/Lean/Parser/Basic.lean b/src/Lean/Parser/Basic.lean
index e0c1690c1f..a13b52536c 100644
--- a/src/Lean/Parser/Basic.lean
+++ b/src/Lean/Parser/Basic.lean
@@ -1469,11 +1469,7 @@ def longestMatchFn (left? : Option Syntax) : List (Parser × Nat) → ParserFn
     let startLhsPrec := s.lhsPrec
     let startPos  := s.pos
     let s         := runLongestMatchParser left? s.lhsPrec p.1.fn c s
-    if s.hasError then
-      let s := s.shrinkStack startSize
-      longestMatchFnAux left? startSize startLhsPrec startPos p.2 ps c s
-    else
-      longestMatchFnAux left? startSize startLhsPrec startPos p.2 ps c s
+    longestMatchFnAux left? startSize startLhsPrec startPos p.2 ps c s
 
 def anyOfFn : List Parser → ParserFn
   | [],    _, s => s.mkError "anyOf: empty list"
diff --git a/tests/lean/tokenErrors.lean.expected.out b/tests/lean/tokenErrors.lean.expected.out
index c3d95dd62f..5a38dadf3c 100644
--- a/tests/lean/tokenErrors.lean.expected.out
+++ b/tests/lean/tokenErrors.lean.expected.out
@@ -6,6 +6,7 @@ tokenErrors.lean:14:0: error: unterminated comment
 tokenErrors.lean:13:0-13:3: error: unexpected doc string
   failed to pretty print term (use 'set_option pp.rawOnError true' for raw representation)
 tokenErrors.lean:17:0: error: unterminated comment
+tokenErrors.lean:16:0-16:6: error: unknown constant '[anonymous]'
 inductive Nat : Type
 constructors:
 Nat.zero : Nat