diff --git a/AlgebraicDataflowArchitectureModel/models/PathParamBug.model b/AlgebraicDataflowArchitectureModel/models/PathParamBug.model
index 3a27bfa..de8c7b5 100644
--- a/AlgebraicDataflowArchitectureModel/models/PathParamBug.model
+++ b/AlgebraicDataflowArchitectureModel/models/PathParamBug.model
@@ -2,7 +2,7 @@
 	out accounts(acs: Map, signUp(id, name)) = insert(acs, id, {"name": name, "friends": nil})
 }
 
-channel makeFriend(aid) {
-	out accounts.{aid}.friends(friends: List, addFreinds(fid)) = append(friends, fid)
-	out accounts.{fid}.friends(friends: List, addFreinds(fid)) = append(friends, aid)
+channel makeFriend(aid: Str) {
+	out accounts.{aid}.friends(friends: List, addFreinds(fid: Str)) = append(friends, fid)
+	out accounts.{fid}.friends(friends: List, addFreinds(fid: Str)) = append(friends, aid)
 }
\ No newline at end of file