diff --git a/compiler/types.nim b/compiler/types.nim
index b57e464443..d9997feba3 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -1525,6 +1525,8 @@ proc typeMismatch*(conf: ConfigRef; info: TLineInfo, formal, actual: PType, n: P
         msg.add "\n.tag effect is 'any tag allowed'"
       of efLockLevelsDiffer:
         msg.add "\nlock levels differ"
+    if formal.kind == tyEnum and actual.kind == tyEnum:
+      msg.add "\nmaybe use `-d:nimLegacyConvEnumEnum` for a transition period"
     localError(conf, info, msg)
 
 proc isTupleRecursive(t: PType, cycleDetector: var IntSet): bool =