diff --git a/core_polymorph.cpp b/core_polymorph.cpp
index a539624..b6adf48 100644
--- a/core_polymorph.cpp
+++ b/core_polymorph.cpp
@@ -260,6 +260,7 @@ Ast *ast_copy(Ast *ast, Ast_Scope *parent_scope, Array<Ast_Decl *> *replace, Arr
 
             dst->args.init(pctx->perm, src->args.len);
             For(src->args) {
+                if (it->flags & AST_POLYMORPH) continue;
                 auto copy = (Ast_Decl *)ast_copy(it, parent_scope, replace, with);
                 dst->args.add(copy);
             }
@@ -276,7 +277,9 @@ Ast *ast_copy(Ast *ast, Ast_Scope *parent_scope, Array<Ast_Decl *> *replace, Arr
         default: assert(!"Invalid default case");
     }
     assert(result);
+
     unset_flag(result->flags, AST_POLYMORPH | AST_PARENT_POLYMORPH);
+
     return result;
 }
 
@@ -355,13 +358,6 @@ Ast_Decl *get_or_instantiate_polymorph_lambda(Token *pos, Ast_Decl *poly, Array<
 
     if (!result) {
         result = (Ast_Decl *)ast_copy(poly, poly->parent_scope, &poly->polymorph_parameters, &params);
-        ForArrayRemovable(result->lambda->args) {
-            ForArrayRemovablePrepare(result->lambda->args);
-            if (it->flags & AST_IDENT_POLYMORPH) {
-                ForArrayRemovableDeclare();
-            }
-        }
-
         result->polymorph_hash = hash;
 
         assert(result->di != poly->di);