diff --git a/src/Lean/Meta/ExprDefEq.lean b/src/Lean/Meta/ExprDefEq.lean
index d1617f86cc..a13207a9cb 100644
--- a/src/Lean/Meta/ExprDefEq.lean
+++ b/src/Lean/Meta/ExprDefEq.lean
@@ -566,7 +566,7 @@ instance : MonadCache Expr Expr CheckAssignmentM := {
 
 private def addAssignmentInfo (msg : MessageData) : CheckAssignmentM MessageData := do
   let ctx ← read
-  return m!" @ {mkMVar ctx.mvarId} {ctx.fvars} := {ctx.rhs}"
+  return m!"{msg} @ {mkMVar ctx.mvarId} {ctx.fvars} := {ctx.rhs}"
 
 @[specialize] def checkFVar (check : Expr → CheckAssignmentM Expr) (fvar : Expr) : CheckAssignmentM Expr := do
   let ctxMeta ← readThe Meta.Context