diff --git a/src/Lean/Parser/Term.lean b/src/Lean/Parser/Term.lean
index 0c24264dc2..2e9afa507a 100644
--- a/src/Lean/Parser/Term.lean
+++ b/src/Lean/Parser/Term.lean
@@ -224,7 +224,7 @@ stx.isAntiquot || stx.isIdent
 @[builtinTermParser] def seqRight    := tparser! infixR " *> "  60
 @[builtinTermParser] def map         := tparser! infixR " <$> " 100
 
-@[builtinTermParser] def byTactic    := parser!:leadPrec "by " >> Tactic.nonEmptySeq
+@[builtinTermParser] def byTactic    := parser!:maxPrec "by " >> Tactic.nonEmptySeq
 
 @[builtinTermParser] def funBinder.quot : Parser := parser! "`(funBinder|"  >> toggleInsideQuot funBinder >> ")"
 end Term
diff --git a/tests/lean/run/new_frontend2.lean b/tests/lean/run/new_frontend2.lean
index b6ddbd1786..4ba6c1684a 100644
--- a/tests/lean/run/new_frontend2.lean
+++ b/tests/lean/run/new_frontend2.lean
@@ -25,3 +25,9 @@ by {
   subst h₁;
   exact rfl
 }
+
+theorem ex : {α : Type} → {a b c : α} → a = b → b = c → a = c :=
+@by {
+  intro α a b c h₁ h₂;
+  exact Eq.trans h₁ h₂
+}